caps_lock.cpp

#include <iostream>
#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define fast_io ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fr(i,a,b) for (int i =a;i<b;i++)
#define loop(x,n) for (int x = 0;x<n;++x)
#define mod 1000000007
#define inf (1LL<<60)
#define all(x) (x).begin(), (x).end()

using namespace std;

void precal(){

}

void solve(){
    string s;
    cin>> s;
    bool check = true;
    for (int i =1;i<s.size();i++){
        if(toupper(s[i])!=s[i])check=false;
    }
    if(check!=false){
        if(s[0]==toupper(s[0])){
            for(auto &i:s)i=tolower(i);
        }
        else{
            s[0]=toupper(s[0]);
            for (int i =1;i<s.size();i++)s[i]=tolower(s[i]);
        }
    }
    cout<<s<<"\n";
}

int main(){
    fast_io;
    cout<<fixed;
    cout<< setprecision(10);
    precal();
    int t =1;
    // cin>> t ;
    for (int i =1;i<=t;i++){
        // cout<< "Case #"<<i<<": ";
        solve();
    }
    return 0;

}