#include <iostream>
#include <string>

using namespace std;

int main()
{
        string password;
        cin >> password;

        for( int i = 0; i < (int)password.length(); i++ )
        {
                if( 'A' <= (int)password[i] && (int)password[i] <= 'Z' )
                {
                        password[i]+=32;
                }
                else if( 'a' <= (int)password[i] && (int)password[i] <= 'z' )
                {
                        password[i]-=32;
                }
                else
                {
                        return 1;
                }
        }

        cout << password <<endl;

        return 0;
}