diff --git a/NumberWithUnits.cpp b/NumberWithUnits.cpp
index e64834d..b56e479 100644
--- a/NumberWithUnits.cpp
+++ b/NumberWithUnits.cpp
@@ -1,38 +1,136 @@
-
 #include <iostream>
 #include <fstream>
 #include <sstream>
 #include <stdexcept>
+#include <map>
+#include <string.h>
 #include "NumberWithUnits.hpp"
-// #define BOOL true 
+// #define BOOL true
+
+using namespace std;
+//m -> cm
+//cm -> m
+//km -> m
+//m -> km
+namespace ariel
+{
+    static map<string, map<string, double>> convertor; // convertor O(3)
 
-// using namespace std;
+    double convertHelp(const string &from, const string &to, double fromVal)
+    {
+        if (from == to)
+        {
+            return fromVal;
+        }
+        if (convertor.at(from).count(to) != 0)
+        {
+            return fromVal * convertor.at(from).at(to);
+        }
+        __throw_invalid_argument("Not valid convertion");
+        
+    }
 
-namespace ariel{
-            void NumberWithUnits::read_units(const ifstream& file){}
-            NumberWithUnits operator+(const NumberWithUnits& unit1, const NumberWithUnits& unit2){return NumberWithUnits();}
-            NumberWithUnits operator+=(const NumberWithUnits& unit1, const NumberWithUnits& unit2){return NumberWithUnits();}
-            NumberWithUnits operator+(const NumberWithUnits& unit){return NumberWithUnits();}
-            NumberWithUnits operator-(const NumberWithUnits& unit1, const NumberWithUnits& unit2){return NumberWithUnits();}
-            NumberWithUnits operator-=(const NumberWithUnits& unit1, const NumberWithUnits& unit2){return NumberWithUnits();}
-            NumberWithUnits operator-(const NumberWithUnits& unit){return NumberWithUnits();}
-            bool operator>(const NumberWithUnits& unit1, const NumberWithUnits& unit2){return unit1.BOOL;}
-            bool operator>=(const NumberWithUnits& unit1, const NumberWithUnits& unit2){return unit1.BOOL;}
-            bool operator<(const NumberWithUnits& unit1, const NumberWithUnits& unit2){return unit1.BOOL;}
-            bool operator<=(const NumberWithUnits& unit1, const NumberWithUnits& unit2){return unit1.BOOL;}
-            bool operator==(const NumberWithUnits& unit1, const NumberWithUnits& unit2){return unit1.BOOL;}
-            bool operator!=(const NumberWithUnits& unit1, const NumberWithUnits& unit2){return unit1.BOOL;}
-            NumberWithUnits operator++(const NumberWithUnits& unit){return NumberWithUnits();}      //Prefix
-            NumberWithUnits operator++(const NumberWithUnits& unit, int){return NumberWithUnits();}     //Postfix
-            NumberWithUnits operator--(const NumberWithUnits& unit){return NumberWithUnits();}      //Prefix
-            NumberWithUnits operator--(const NumberWithUnits& unit, int){return NumberWithUnits();}     //Postfix
-            NumberWithUnits operator*(const NumberWithUnits& unit, double num){return NumberWithUnits();}
-            NumberWithUnits operator*(double num, const NumberWithUnits& unit){return NumberWithUnits();}
-            ostream& operator<<(const ostream& os, const NumberWithUnits& unit){return cout << unit._value << "[" << unit._unit << "]" << endl;}
-            istream& operator>>(std::istream& in, NumberWithUnits& unit){
-                string s;
-                in >> unit._value >> s >> unit._unit;
-                return in;
+    double convert(const string &from, const string &to, double fromVal)
+    {
+        if (from == to)
+        {
+            return fromVal;
+        }
+        if (convertor.at(from).count(to) != 0)
+        {
+            return fromVal * convertor.at(from).at(to);
+        }
+        map<string, double> m = convertor.at(from);
+        string s;
+        for (map<string, double>::iterator it = m.begin(); it != m.end(); ++it)
+        {
+            s = it->first;
+        }
+        return convertHelp(s, to, convert(from, s, fromVal));
+    }
+
+    void NumberWithUnits::read_units(ifstream &file)
+    {
+        double Dunit1 = 0;
+        double Dunit2 = 0;
+        string Munit1;
+        string Munit2;
+        string none;
+        string line;
+        while (getline(file, line))
+        {
+            istringstream Sstream(line);
+            if (!(Sstream >> Dunit1 >> Munit1 >> none >> Dunit2 >> Munit2))
+            {
+                break;
             }
-}
 
+            convertor[Munit1][Munit2] = Dunit2;     //from
+            convertor[Munit2][Munit1] = 1 / Dunit2; //to
+        }
+    }
+
+    NumberWithUnits operator+(const NumberWithUnits &unit1, const NumberWithUnits &unit2)
+    {
+        double converted = convert(unit2._unit, unit1._unit, unit2._value);
+        return NumberWithUnits(unit1._value + converted, unit1._unit);
+    }
+    NumberWithUnits operator+=(NumberWithUnits &unit1, const NumberWithUnits &unit2)
+    {
+        unit1._value += convert(unit2._unit, unit1._unit, unit2._value);
+        return unit1;
+    }
+    NumberWithUnits operator+(const NumberWithUnits &unit, double num)
+    {
+        return NumberWithUnits(unit._value + num, unit._unit);
+    }
+    NumberWithUnits operator-(const NumberWithUnits &unit1, const NumberWithUnits &unit2)
+    {
+        double converted = convert(unit2._unit, unit1._unit, unit2._value);
+        return NumberWithUnits(unit1._value - converted, unit1._unit);
+    }
+    NumberWithUnits operator-=(NumberWithUnits &unit1, const NumberWithUnits &unit2)
+    {
+        unit1._value -= convert(unit2._unit, unit1._unit, unit2._value);
+        return unit1;
+    }
+    NumberWithUnits operator-(const NumberWithUnits &unit)
+    {
+        return NumberWithUnits(-unit._value, unit._unit);
+    }
+    int compare(const NumberWithUnits &n1, const NumberWithUnits &n2)
+    {
+        double x = n1._value - convert(n2._unit, n1._unit, n2._value);
+        double y = convert(n2._unit, n1._unit, n2._value) - n1._value;
+        const double epsilon = 0.00001;
+        if (x > epsilon)
+        {
+            return 1;
+        }
+        if (y > epsilon)
+        {
+            return -1;
+        }
+        return 0;
+    }
+
+    bool operator>(const NumberWithUnits &unit1, const NumberWithUnits &unit2) { return compare(unit1, unit2) > 0; }
+    bool operator>=(const NumberWithUnits &unit1, const NumberWithUnits &unit2) { return compare(unit1, unit2) >= 0; }
+    bool operator<(const NumberWithUnits &unit1, const NumberWithUnits &unit2) { return compare(unit1, unit2) < 0; }
+    bool operator<=(const NumberWithUnits &unit1, const NumberWithUnits &unit2) { return compare(unit1, unit2) <= 0; }
+    bool operator==(const NumberWithUnits &unit1, const NumberWithUnits &unit2) { return compare(unit1, unit2) == 0; }
+    bool operator!=(const NumberWithUnits &unit1, const NumberWithUnits &unit2) { return compare(unit1, unit2) != 0; }
+    NumberWithUnits operator++(NumberWithUnits &unit) { return NumberWithUnits(++unit._value, unit._unit); }      //Prefix
+    NumberWithUnits operator++(NumberWithUnits &unit, int) { return NumberWithUnits(unit._value++, unit._unit); } //Postfix
+    NumberWithUnits operator--(NumberWithUnits &unit) { return NumberWithUnits(--unit._value, unit._unit); }      //Prefix
+    NumberWithUnits operator--(NumberWithUnits &unit, int) { return NumberWithUnits(unit._value++, unit._unit); } //Postfix
+    NumberWithUnits operator*(const NumberWithUnits &unit, double num) { return NumberWithUnits(num * unit._value, unit._unit); }
+    NumberWithUnits operator*(double num, const NumberWithUnits &unit) { return NumberWithUnits(num * unit._value, unit._unit); }
+    ostream &operator<<(const ostream &os, const NumberWithUnits &unit) { return cout << unit._value << "[" << unit._unit << "]" << endl; }
+    istream &operator>>(std::istream &in, NumberWithUnits &unit)
+    {
+        string s;
+        in >> unit._value >> s >> unit._unit;
+        return in;
+    }
+}
diff --git a/NumberWithUnits.hpp b/NumberWithUnits.hpp
index f3c64e9..46acb45 100644
--- a/NumberWithUnits.hpp
+++ b/NumberWithUnits.hpp
@@ -16,12 +16,15 @@ namespace ariel{
                 }
                 NumberWithUnits(){}
                 ~NumberWithUnits(){}
-                static void read_units(const ifstream& file);
+                friend int compare(const NumberWithUnits& n1, const NumberWithUnits& n2);
+                double convert(const string &from, const string &to, double fromVal);
+                double convertHelp(const string &from, const string &to, double fromVal);
+                static void read_units(ifstream& file);
                 friend NumberWithUnits operator+(const NumberWithUnits& unit1, const NumberWithUnits& unit2);
-                friend NumberWithUnits operator+=(const NumberWithUnits& unit1, const NumberWithUnits& unit2);
-                friend NumberWithUnits operator+(const NumberWithUnits& unit);
+                friend NumberWithUnits operator+=(NumberWithUnits& unit1, const NumberWithUnits& unit2);
+                friend NumberWithUnits operator+(const NumberWithUnits& unit, double num);
                 friend NumberWithUnits operator-(const NumberWithUnits& unit1, const NumberWithUnits& unit2);
-                friend NumberWithUnits operator-=(const NumberWithUnits& unit1, const NumberWithUnits& unit2);
+                friend NumberWithUnits operator-=(NumberWithUnits& unit1, const NumberWithUnits& unit2);
                 friend NumberWithUnits operator-(const NumberWithUnits& unit);
                 friend bool operator>(const NumberWithUnits& unit1, const NumberWithUnits& unit2);
                 friend bool operator>=(const NumberWithUnits& unit1, const NumberWithUnits& unit2);
@@ -29,10 +32,10 @@ namespace ariel{
                 friend bool operator<=(const NumberWithUnits& unit1, const NumberWithUnits& unit2);
                 friend bool operator==(const NumberWithUnits& unit1, const NumberWithUnits& unit2);
                 friend bool operator!=(const NumberWithUnits& unit1, const NumberWithUnits& unit2);
-                friend NumberWithUnits operator++(const NumberWithUnits& unit);       //Prefix
-                friend NumberWithUnits operator++(const NumberWithUnits& unit, int);     //Postfix
-                friend NumberWithUnits operator--(const NumberWithUnits& unit);       //Prefix
-                friend NumberWithUnits operator--(const NumberWithUnits& unit, int);     //Postfix
+                friend NumberWithUnits operator++( NumberWithUnits& unit);       //Prefix
+                friend NumberWithUnits operator++( NumberWithUnits& unit, int);     //Postfix
+                friend NumberWithUnits operator--( NumberWithUnits& unit);       //Prefix
+                friend NumberWithUnits operator--( NumberWithUnits& unit, int);     //Postfix
                 friend NumberWithUnits operator*(const NumberWithUnits& unit, double num);
                 friend NumberWithUnits operator*(double num, const NumberWithUnits& unit);
                 friend ostream& operator<<(const ostream& os, const NumberWithUnits& unit);
diff --git a/Test.cpp b/Test.cpp
index 3ab40a6..3b7859a 100644
--- a/Test.cpp
+++ b/Test.cpp
@@ -13,6 +13,7 @@ static vector<string> units = {"m"};
 ifstream units_file{"units.txt"};
 
 TEST_CASE("Multi operators"){
+    NumberWithUnits::read_units(units_file);
     NumberWithUnits a{1, "m"};
     NumberWithUnits b{3, "m"};
     NumberWithUnits c{300, "cm"};
@@ -42,17 +43,18 @@ TEST_CASE("All bool operators"){
     CHECK(d>=c);
     CHECK(c>=e);
     CHECK(e>=c);
-    CHECK(a<d);
+    CHECK(c<d);
     NumberWithUnits f{1, "kg"};
     NumberWithUnits g{1000, "g"};
-    CHECK_FALSE(b!=a);
+    CHECK_FALSE(f!=g);
     CHECK(g==f);
     CHECK(g<=f);
-    NumberWithUnits h{0.0001, "ton"};
+    NumberWithUnits h{0.001, "ton"};
     CHECK(f==h);
     CHECK(f==g);
-    NumberWithUnits i{0.0002, "ton"};
+    NumberWithUnits i{0.002, "ton"};
     CHECK(f!=i);
+    g++;
     CHECK(f!=g);
 }
 
@@ -67,13 +69,13 @@ TEST_CASE("+, -, +="){
     CHECK((b+=a)==c);
     CHECK((a+=c)==d);
     CHECK_FALSE((b+=a)==d);
-    NumberWithUnits e{0.5, "km"};
+    NumberWithUnits e{1, "km"};
     NumberWithUnits a2{2, "km"};
     NumberWithUnits b2{1000, "m"};
     CHECK((a2-b2)==e);
     NumberWithUnits f{500, "m"};
-    CHECK((b2-a2)==e);
-    CHECK((b2-a2)==f);
+    CHECK((b2-a2)==-e);
+    CHECK((b2-a2)==-(f*2));
 }
 
 TEST_CASE("Postfix and Prefix operators (++/--)"){
@@ -82,10 +84,9 @@ TEST_CASE("Postfix and Prefix operators (++/--)"){
     NumberWithUnits c{180, "min"};
     CHECK(++a==b);
     CHECK(++a==c);
-    CHECK(a++==a);
-    NumberWithUnits d{3, "hour"};
+    CHECK_FALSE(a++==a);
+    NumberWithUnits d{4, "hour"};
     CHECK(a==d);
     CHECK(--a==++b); 
     CHECK(a--==b);
-}
-
+}
\ No newline at end of file
diff --git a/number-with-units-a.rar:Zone.Identifier b/number-with-units-a.rar:Zone.Identifier
new file mode 100644
index 0000000..053d112
--- /dev/null
+++ b/number-with-units-a.rar:Zone.Identifier
@@ -0,0 +1,3 @@
+[ZoneTransfer]
+ZoneId=3
+HostUrl=about:internet