diff --git a/src/main/java/me/alex4386/gachon/network/common/http/HttpRequest.java b/src/main/java/me/alex4386/gachon/network/common/http/HttpRequest.java
new file mode 100644
index 0000000..1613f0c
--- /dev/null
+++ b/src/main/java/me/alex4386/gachon/network/common/http/HttpRequest.java
@@ -0,0 +1,96 @@
+package me.alex4386.gachon.network.common.http;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.util.HashMap;
+import java.util.Map;
+
+public class HttpRequest {
+    // 귀찮으니까 학교 과제물 낸걸로 대충 때워
+    // Removed JSON Dependencies Edition
+
+    HttpRequestMethod method;
+    URL url;
+
+    String body = null;
+    Map<String, String> headers = new HashMap<>();
+
+    boolean enableDebug = false;
+
+    public HttpRequest(HttpRequestMethod method, URL url) {
+        this.method = method;
+        this.url = url;
+    }
+
+    public HttpRequest(HttpRequestMethod method, URL url, String contentType, String body) {
+        this.method = method;
+        this.url = url;
+
+        this.body = body;
+
+        headers.put("Content-Type", contentType);
+    }
+
+    public void addHeaders(Map<String, String> headers) {
+        for (Map.Entry<String, String> header : headers.entrySet()) {
+            String key = header.getKey();
+
+            if (this.headers.containsKey(key)) {
+                this.headers.remove(key);
+            }
+
+            this.headers.put(key, header.getValue());
+        }
+    }
+
+    public void setHeaders(Map<String, String> headers) {
+        this.headers = headers;
+    }
+
+    public boolean isDebug() {
+        return this.enableDebug;
+    }
+
+    public void setDebug(boolean debug) {
+        this.enableDebug = debug;
+    }
+
+    public HttpResponse getResponse() throws IOException {
+        HttpURLConnection conn = (HttpURLConnection) this.url.openConnection();
+        conn.setRequestMethod(this.method.toString());
+
+        for (Map.Entry<String, String> headerEntry : this.headers.entrySet()) {
+            conn.setRequestProperty(headerEntry.getKey(), headerEntry.getValue());
+        }
+
+        if (this.enableDebug) {
+            System.out.println(this.method.toString()+" "+this.url.toString());
+        }
+
+        if (body != null) {
+            if (this.enableDebug) {
+                System.out.println(body);
+            }
+
+            conn.setDoOutput(true);
+
+            OutputStream outputStream = conn.getOutputStream();
+            OutputStreamWriter writer = new OutputStreamWriter(outputStream, "UTF-8");
+
+            writer.write(body);
+
+            writer.flush();
+            writer.close();
+        }
+
+        conn.connect();
+
+        HttpResponse response = new HttpResponse(conn);
+
+        return response;
+    }
+}
+
diff --git a/src/main/java/me/alex4386/gachon/network/common/http/HttpRequestMethod.java b/src/main/java/me/alex4386/gachon/network/common/http/HttpRequestMethod.java
new file mode 100644
index 0000000..7f79b83
--- /dev/null
+++ b/src/main/java/me/alex4386/gachon/network/common/http/HttpRequestMethod.java
@@ -0,0 +1,23 @@
+package me.alex4386.gachon.network.common.http;
+
+public enum HttpRequestMethod {
+    GET("GET"),
+    HEAD("HEAD"),
+    POST("POST"),
+    PUT("PUT"),
+    PATCH("PATCH"),
+    DELETE("DELETE"),
+    OPTIONS("OPTIONS"),
+    TRACE("TRACE");
+
+    private String rawString;
+
+    HttpRequestMethod(String raw) {
+        this.rawString = raw;
+    }
+
+    @Override
+    public String toString() {
+        return this.rawString;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/me/alex4386/gachon/network/common/http/HttpResponse.java b/src/main/java/me/alex4386/gachon/network/common/http/HttpResponse.java
new file mode 100644
index 0000000..797cdb2
--- /dev/null
+++ b/src/main/java/me/alex4386/gachon/network/common/http/HttpResponse.java
@@ -0,0 +1,56 @@
+package me.alex4386.gachon.network.common.http;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+
+public class HttpResponse {
+    public HttpResponseCode code;
+    public String response;
+
+    boolean enableDebug = false;
+
+    public HttpResponse(HttpURLConnection conn) throws IOException {
+        int responseCode = conn.getResponseCode();
+        this.code = HttpResponseCode.getResponse(responseCode);
+
+        BufferedReader bufReader;
+
+        if (this.code.isOK()) {
+            bufReader = new BufferedReader(
+                    new InputStreamReader(
+                            conn.getInputStream()
+                    )
+            );
+        } else {
+            bufReader = new BufferedReader(
+                    new InputStreamReader(
+                            conn.getErrorStream()
+                    )
+            );
+        }
+
+        StringBuilder stringBuilder = new StringBuilder();
+        String thisLine;
+        while ((thisLine = bufReader.readLine()) != null) {
+            stringBuilder.append(thisLine);
+            stringBuilder.append("\n");
+        }
+
+        bufReader.close();
+        conn.disconnect();
+
+        this.response = stringBuilder.toString();
+
+        if (this.enableDebug) {
+            System.out.println("Code: "+this.code.getCode());
+            System.out.println("Resp: \n"+this.response);
+        }
+    }
+
+    @Override
+    public String toString() {
+        return this.response;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/me/alex4386/gachon/network/common/http/HttpResponseCode.java b/src/main/java/me/alex4386/gachon/network/common/http/HttpResponseCode.java
new file mode 100644
index 0000000..22fb8c1
--- /dev/null
+++ b/src/main/java/me/alex4386/gachon/network/common/http/HttpResponseCode.java
@@ -0,0 +1,127 @@
+package me.alex4386.gachon.network.common.http;
+
+public enum HttpResponseCode {
+    /* Informational */
+    CONTINUE(100, "Continue"),
+    SWITCHING_PROTOCOLS(101, "Switching Protocols"),
+    PROCESSING(102, "Processing"),
+    EARLY_HINTS(103, "Early Hints"),
+
+    /* Success */
+    OK(200, "OK"),
+    CREATED(201, "Created"),
+    ACCEPTED(202, "Accepted"),
+    NON_AUTHORITATIVE_INFORMATION(203, "Non-Authoritative Information"),
+    NO_CONTENT(204, "No Content"),
+    RESET_CONTENT(205, "Reset Content"),
+    PARTIAL_CONTENT(206, "Partial Content"),
+    MULTI_STATUS(207, "Multi-Status"),
+    ALREADY_REPORTED(208, "Already Reported"),
+    IM_USED(226, "IM Used"),
+
+    /* Redirection */
+    MULTIPLE_CHOICES(300, "Multiple Choices"),
+    MOVED_PERMANENTLY(301, "Moved Permanently"),
+    FOUND(302, "Found"),
+    SEE_OTHER(303, "See Other"),
+    NOT_MODIFIED(304, "Not Modified"),
+    USE_PROXY(305, "Use Proxy"),
+    TEMPORARY_REDIRECT(307, "Temporary Redirect"),
+    PERMANENT_REDIRECT(308, "Permanent Redirect"),
+
+    /* Client Error */
+    BAD_REQUEST(400, "Bad Request"),
+    UNAUTHORIZED(401, "Unauthorized"),
+    PAYMENT_REQUIRED(402, "Payment Required"),
+    FORBIDDEN(403, "Forbidden"),
+    NOT_FOUND(404, "Not Found"),
+    METHOD_NOT_ALLOWED(405, "Method Not Allowed"),
+    NOT_ACCEPTABLE(406, "Not Acceptable"),
+    PROXY_AUTHENTICATION_REQUIRED(407, "Proxy Authentication Required"),
+    REQUEST_TIMEOUT(408, "Request Timeout"),
+    CONFLICT(409, "Conflict"),
+    GONE(410, "Gone"),
+    LENGTH_REQUIRED(411, "Length Required"),
+    PRECONDITION_FAILED(412, "Precondition Failed"),
+    PAYLOAD_TOO_LARGE(413, "Payload Too Large"),
+    URI_TOO_LONG(414, "URI Too Long"),
+    UNSUPPORTED_MEDIA_TYPE(415, "Unsupported Media Type"),
+    REQUEST_RANGE_NOT_SATISFIABLE(416, "Request Range Not Satisfiable"),
+    EXPECTATION_FAILED(417, "Expectation Failed"),
+    IM_A_TEAPOT(418, "I'm a teapot"),
+    UNPROCESSABLE_ENTITY(422, "Unprocessable Entity"),
+    LOCKED(423, "Precondition Failed"),
+    FAILED_DEPENDENCY(424, "Precondition Failed"),
+    TOO_EARLY(425, "Too Early"),
+    UPGRADE_REQUIRED(426, "Upgrade Required"),
+    PRECONDITION_REQUIRED(428, "Precondition Required"),
+    TOO_MANY_REQUESTS(429, "Too Many Requests"),
+    REQUEST_HEADER_FIELDS_TOO_LARGE(431, "Request Header Fields Too Large"),
+    @Deprecated
+    NO_RESPONSE(444, "No Response"),
+    @Deprecated
+    RETRY_WITH(449, "Retry With"),
+    @Deprecated
+    BLOCKED_BY_WINDOWS_PARENTAL_CONTROLS(450, "Blocked by Windows Parental Controls"),
+    UNAVAILABLE_FOR_LEGAL_REASONS(451, "Precondition Failed"),
+    @Deprecated
+    CLIENT_CLOSED_REQUEST(499, "Client Closed Request"),
+
+    /* Server Error */
+    INTERNAL_SERVER_ERROR(500, "Internal Server Error"),
+    NOT_IMPLEMENTED(501, "Not Implemented"),
+    BAD_GATEWAY(502, "Bad Gateway"),
+    SERVICE_UNAVAILABLE(503, "Service Unavailable"),
+    GATEWAY_TIMEOUT(504, "Gateway Timeout"),
+    HTTP_VERSION_NOT_SUPPORTED(505, "HTTP Version Not Supported"),
+    VARIANT_ALSO_NEGOTIATES(506, "Variant Also Negotiates"),
+    INSUFFICIENT_STORAGE(507, "Insufficient Storage"),
+    LOOP_DETECTED(508, "Loop Detected"),
+    BANDWIDTH_LIMIT_EXCEEDED(509, "Bandwidth Limit Exceeded"),
+    NOT_EXTENDED(510, "Not Extended"),
+    NETWORK_AUTHENTICATION_REQUIRED(511, "Network Authentication Required");
+
+    private int code;
+    private String name;
+
+    HttpResponseCode(int code, String name) {
+        this.code = code;
+        this.name = name;
+    }
+
+    public boolean isOK() {
+        return code == 200;
+    }
+
+    public boolean isSuccess() {
+        return 200 <= code && code < 300;
+    }
+
+    public boolean isClientError() {
+        return 400 <= code && code < 499;
+    }
+
+    public boolean isServerError() {
+        return 500 <= code && code < 599;
+    }
+
+    public int getCode() {
+        return this.code;
+    }
+
+    @Override
+    public String toString() {
+        return name;
+    }
+
+    public static HttpResponseCode getResponse(int code) {
+        for (HttpResponseCode respCode : HttpResponseCode.values()) {
+            if (code == respCode.code) {
+                return respCode;
+            }
+        }
+
+        return null;
+    }
+
+}
\ No newline at end of file
diff --git a/src/main/java/me/alex4386/gachon/sw14462/Main.java b/src/main/java/me/alex4386/gachon/sw14462/Main.java
index e919e50..db42bd0 100644
--- a/src/main/java/me/alex4386/gachon/sw14462/Main.java
+++ b/src/main/java/me/alex4386/gachon/sw14462/Main.java
@@ -5,7 +5,7 @@
 import java.util.*;
 
 public class Main {
-    public static String currentTarget = "day23";
+    public static String currentTarget = "day24";
     public static boolean fallbackToLatest = true;
 
     public static Map<String, Class<?>> getAvailableTargetClassNames() {
diff --git a/src/main/java/me/alex4386/gachon/sw14462/day24/Main.java b/src/main/java/me/alex4386/gachon/sw14462/day24/Main.java
new file mode 100644
index 0000000..8c05df7
--- /dev/null
+++ b/src/main/java/me/alex4386/gachon/sw14462/day24/Main.java
@@ -0,0 +1,19 @@
+package me.alex4386.gachon.sw14462.day24;
+
+import me.alex4386.gachon.sw14462.utils.Chainloader;
+
+public class Main {
+    public static String chainloadTarget = "ex13_9";
+
+    public static void main(String[] args) throws Throwable {
+        String packageName = Main.class.getPackage().getName();
+        String chainLoadTargetClass = packageName + "." + chainloadTarget + ".Main";
+
+        try {
+            Chainloader.chainloadTarget(chainLoadTargetClass, args);
+        } catch (Exception e) {
+            throw e;
+        }
+    }
+
+}
diff --git a/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_2/Main.java b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_2/Main.java
new file mode 100644
index 0000000..b959094
--- /dev/null
+++ b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_2/Main.java
@@ -0,0 +1,61 @@
+package me.alex4386.gachon.sw14462.day24.ex13_2;
+
+import java.io.File;
+import java.io.PrintWriter;
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        File in = new File("in");
+        File out = new File("out");
+
+        if (!in.exists()) {
+            System.err.println("File named 'in' not found");
+            System.exit(1);
+        }
+
+        if (out.exists()) {
+            out.delete();
+        }
+
+        try {
+            out.createNewFile();
+        } catch (Exception e) {
+            System.err.println("Failed to create file: " + e.getMessage());
+            return;
+        }
+
+        // assume that the numbers in the input file are already ordered from smallest to largest:
+        // which means the number came beforehand is same with current number, it is a duplicate.
+
+        // read the file
+        int prevInt = 0;
+        try {
+            Scanner scanner = new Scanner(in);
+            PrintWriter writer = new PrintWriter(out);
+
+            boolean isFirst = true;
+
+            while (scanner.hasNextInt()) {
+                int currentInt = scanner.nextInt();
+
+                if (isFirst) {
+                    isFirst = false;
+                    prevInt = currentInt;
+                    writer.println(currentInt);
+                } else {
+                    if (prevInt != currentInt) {
+                        writer.println(currentInt);
+                        prevInt = currentInt;
+                    }
+                }
+            }
+
+            scanner.close();
+            writer.close();
+        } catch (Exception e) {
+            System.err.println("Failed to read/write file: " + e.getMessage());
+            return;
+        }
+    }
+}
diff --git a/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_2a/Main.java b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_2a/Main.java
new file mode 100644
index 0000000..b0ede3d
--- /dev/null
+++ b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_2a/Main.java
@@ -0,0 +1,94 @@
+package me.alex4386.gachon.sw14462.day24.ex13_2a;
+
+import java.io.*;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+public class Main {
+
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+
+        System.out.print("Enter the filename: ");
+        String filename = scanner.nextLine();
+
+        // generate 10 random integer
+        int[] randomIntegers = new int[10];
+        for (int i = 0; i < 10; i++) {
+            randomIntegers[i] = (int) (Math.random() * 1000);
+        }
+
+        // write to file
+        File targetFile = new File(filename);
+        if (targetFile.exists()) {
+            // unlink the file
+            targetFile.delete();
+        }
+
+        FileOutputStream stream;
+        ObjectOutputStream writer;
+        try {
+            targetFile.createNewFile();
+            stream = new FileOutputStream(targetFile);
+            writer = new ObjectOutputStream(stream);
+        } catch (Exception e) {
+            System.err.println("Failed to create file: " + e.getMessage());
+            return;
+        }
+
+        try {
+            writer.writeObject(randomIntegers);
+        } catch (IOException e) {
+            System.err.println("Failed to write object: " + e.getMessage());
+            return;
+        }
+
+        System.out.println("File created successfully.");
+        scanner.close();
+
+        // reopen the file
+        targetFile = new File(filename);
+        if (!targetFile.exists()) {
+            System.err.println("File does not exists, is the file has been deleted in the meantime?");
+            return;
+        }
+
+        try {
+            scanner = new Scanner(targetFile);
+        } catch (Exception e) {
+            System.err.println("Failed to open file: " + e.getMessage());
+            return;
+        }
+
+        int[] readIntegers = null;
+        try {
+            FileInputStream fileInputStream = new FileInputStream(targetFile);
+            ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
+            readIntegers = (int[]) objectInputStream.readObject();
+            objectInputStream.close();
+        } catch (Exception e) {
+            System.err.println("Failed to read object: " + e.getMessage());
+            return;
+        }
+
+        int count = 0;
+        int min = Integer.MAX_VALUE, max = Integer.MIN_VALUE, sum = 0;
+        double average;
+
+        for (int val : readIntegers) {
+            count++;
+            sum += val;
+            if (val < min) min = val;
+            if (val > max) max = val;
+        }
+
+        average = (double) sum / count;
+        scanner.close();
+
+        System.out.println("min: "+min);
+        System.out.println("max: "+max);
+        System.out.println("sum: "+sum);
+        System.out.println("average: "+average);
+    }
+}
diff --git a/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_2b/Main.java b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_2b/Main.java
new file mode 100644
index 0000000..7665241
--- /dev/null
+++ b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_2b/Main.java
@@ -0,0 +1,120 @@
+package me.alex4386.gachon.sw14462.day24.ex13_2b;
+
+import java.io.*;
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        File signalFile = new File("signal.txt");
+        if (!signalFile.exists()) {
+            System.err.println("Signal file not found: signal.txt");
+            System.exit(1);
+        }
+
+        int[] readIntegers = new int[10];
+        FileInputStream stream;
+        Scanner scanner;
+        try {
+            stream = new FileInputStream(signalFile);
+            scanner = new Scanner(stream);
+        } catch (Exception e) {
+            System.err.println("Failed to open file: " + e.getMessage());
+            return;
+        }
+
+        try {
+            for (int i = 0; i < 10; i++) {
+                readIntegers[i] = scanner.nextInt();
+            }
+        } catch (Exception e) {
+            System.err.println("Failed to read file: " + e.getMessage());
+            return;
+        }
+
+        scanner.close();
+
+        File outputFile = new File("signal.out");
+        if (outputFile.exists()) {
+            outputFile.delete();
+        }
+
+        FileOutputStream outputStream;
+        try {
+            outputFile.createNewFile();
+            outputStream = new FileOutputStream(outputFile);
+        } catch (Exception e) {
+            System.err.println("Failed to create file: " + e.getMessage());
+            return;
+        }
+
+        ObjectOutputStream objOutStream;
+        int[] diffIntegers = new int[10];
+        diffIntegers[0] = readIntegers[0];
+        for (int i = 1; i < 10; i++) {
+            int diff = readIntegers[i] - readIntegers[i - 1];
+            if (diff > 128 || diff < -127) {
+                System.err.println("Value out of range: " + diff);
+                return;
+            }
+
+            diffIntegers[i] = diff;
+        }
+
+        try {
+            objOutStream = new ObjectOutputStream(outputStream);
+            objOutStream.writeObject(diffIntegers);
+        } catch (Exception e) {
+            System.err.println("Failed to write object: " + e.getMessage());
+            return;
+        }
+
+        try {
+            objOutStream.close();
+        } catch (Exception e) {
+            System.err.println("Failed to close file: " + e.getMessage());
+            return;
+        }
+
+        File targetFile = new File("signal.exp");
+        try {
+            if (!targetFile.exists()) {
+                targetFile.createNewFile();
+            } else {
+                targetFile.delete();
+                targetFile.createNewFile();
+            }
+        } catch (IOException e) {
+            System.err.println("Failed to create file: " + e.getMessage());
+            return;
+        }
+
+        // read back
+        FileInputStream fileInputStream;
+        ObjectInputStream objInStream;
+
+        try {
+            fileInputStream = new FileInputStream(outputFile);
+            objInStream = new ObjectInputStream(fileInputStream);
+        } catch (Exception e) {
+            System.err.println("Failed to open file: " + e.getMessage());
+            return;
+        }
+
+        int[] exportedIntegers = null;
+        try {
+            exportedIntegers = (int[]) objInStream.readObject();
+        } catch (Exception e) {
+            System.err.println("Failed to read object: " + e.getMessage());
+            return;
+        }
+
+        // process exported integers
+        for (int i = 1; i < 10; i++) {
+            exportedIntegers[i] += exportedIntegers[i - 1];
+        }
+
+        for (int i = 0; i < 10; i++) {
+            System.out.println(exportedIntegers[i]);
+        }
+    }
+}
diff --git a/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_3/Main.java b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_3/Main.java
new file mode 100644
index 0000000..8c9674b
--- /dev/null
+++ b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_3/Main.java
@@ -0,0 +1,32 @@
+package me.alex4386.gachon.sw14462.day24.ex13_3;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        File wordFile = new File("words.txt");
+
+        if (!wordFile.exists()) {
+            System.err.println("Word file not found: words.txt");
+            System.exit(1);
+        }
+
+        Scanner scanner;
+        try {
+            scanner = new Scanner(wordFile);
+        } catch(IOException e) {
+            System.err.println("Failed to open file: " + e.getMessage());
+            return;
+        }
+
+        while (scanner.hasNextLine()) {
+            String word = scanner.nextLine();
+            if (word.endsWith("dous")) {
+                System.out.println(word);
+            }
+        }
+
+    }
+}
diff --git a/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_5/Main.java b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_5/Main.java
new file mode 100644
index 0000000..ec59490
--- /dev/null
+++ b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_5/Main.java
@@ -0,0 +1,54 @@
+package me.alex4386.gachon.sw14462.day24.ex13_5;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        File abbreviationFile = new File("abbreviations.txt");
+        if (!abbreviationFile.exists()) {
+            System.err.println("Abbreviation file not found: abbreviations.txt");
+            System.err.println("Falling back to jar file internal...");
+
+            System.exit(1);
+        }
+
+        File chatFile = new File("chat.txt");
+        if (!chatFile.exists()) {
+            System.err.println("Chat file not found: chat.txt");
+            System.exit(1);
+        }
+
+        // wrap words (seperated by line) specified in abbreviations file with <> in chat file
+        List<String> abbreviations = new ArrayList<>();
+        try {
+            Scanner scanner = new Scanner(abbreviationFile);
+            while (scanner.hasNextLine()) {
+                abbreviations.add(scanner.nextLine());
+            }
+            scanner.close();
+        } catch (Exception e) {
+            System.err.println("Failed to read abbreviations file: " + e.getMessage());
+            return;
+        }
+
+        try {
+            Scanner scanner = new Scanner(chatFile);
+            while (scanner.hasNextLine()) {
+                String line = scanner.nextLine();
+                for (String abbreviation : abbreviations) {
+                    // escape regex for special characters
+                    String abbreviationEscaped = abbreviation.replaceAll("([\\[\\]\\{\\}\\(\\)\\*\\+\\?\\^\\$\\.\\|])", "\\\\$1");
+                    line = line.replaceAll(abbreviationEscaped, "<" + abbreviation + ">");
+                }
+                System.out.println(line);
+            }
+            scanner.close();
+        } catch (Exception e) {
+            System.err.println("Failed to read chat file: " + e.getMessage());
+            return;
+        }
+    }
+}
diff --git a/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_9/Main.java b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_9/Main.java
new file mode 100644
index 0000000..2ec2244
--- /dev/null
+++ b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_9/Main.java
@@ -0,0 +1,64 @@
+package me.alex4386.gachon.sw14462.day24.ex13_9;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        InputStream stream;
+        File file = new File("haberman.csv");
+        try {
+            stream = new FileInputStream(file);
+        } catch (IOException e) {
+            System.err.println("Failed to load following file: haberman.csv");
+            System.err.println("Fallback to jar file...");
+
+            stream = Main.class.getResourceAsStream("/day24/ex13_9/haberman.csv");
+            if (stream == null) {
+                System.err.println("Failed to load following resource from jar file: haberman.csv");
+                return;
+            }
+        }
+
+        Scanner scanner = new Scanner(stream);
+        List<SurgeryData> data = new ArrayList<>();
+
+        while (scanner.hasNextLine()) {
+            String csv = scanner.nextLine();
+            SurgeryData surgeryData = SurgeryData.fromCSV(csv);
+            if (surgeryData != null) {
+                data.add(surgeryData);
+            }
+        }
+
+        // calculates the average number of positive axillary nodes detected for
+        // patients who survived 5 years or longer
+        int totalNodes = 0;
+        int totalPatients = 0;
+        for (SurgeryData surgeryData : data) {
+            if (surgeryData.getSurvival() == 1) {
+                totalNodes += surgeryData.getNodes();
+                totalPatients++;
+            }
+        }
+
+        System.out.println("Average number of positive axillary nodes detected for patients who survived 5 years or longer: " + (totalNodes / totalPatients));
+
+        // the average number of positive axillary nodes detected for patients who died within 5 years
+        totalNodes = 0;
+        totalPatients = 0;
+        for (SurgeryData surgeryData : data) {
+            if (surgeryData.getSurvival() == 2) {
+                totalNodes += surgeryData.getNodes();
+                totalPatients++;
+            }
+        }
+
+        System.out.println("Average number of positive axillary nodes detected for patients who died within 5 years: " + (totalNodes / totalPatients));
+    }
+}
diff --git a/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_9/SurgeryData.java b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_9/SurgeryData.java
new file mode 100644
index 0000000..4874e6f
--- /dev/null
+++ b/src/main/java/me/alex4386/gachon/sw14462/day24/ex13_9/SurgeryData.java
@@ -0,0 +1,41 @@
+package me.alex4386.gachon.sw14462.day24.ex13_9;
+
+public class SurgeryData {
+    private int age;
+    private int year;
+    private int nodes;
+    private int survival;
+
+    public SurgeryData(int age, int year, int nodes, int survival) {
+        this.age = age;
+        this.year = year;
+        this.nodes = nodes;
+        this.survival = survival;
+    }
+
+    public static SurgeryData fromCSV(String csv) {
+        String[] data = csv.split(",");
+        return new SurgeryData(
+            Integer.parseInt(data[0]),
+            Integer.parseInt(data[1]),
+            Integer.parseInt(data[2]),
+            Integer.parseInt(data[3])
+        );
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public int getYear() {
+        return year;
+    }
+
+    public int getNodes() {
+        return nodes;
+    }
+
+    public int getSurvival() {
+        return survival;
+    }
+}
diff --git a/src/main/resources/day24/ex13_9/haberman.csv b/src/main/resources/day24/ex13_9/haberman.csv
new file mode 100755
index 0000000..1052439
--- /dev/null
+++ b/src/main/resources/day24/ex13_9/haberman.csv
@@ -0,0 +1,306 @@
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