#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
    char a;
    cin>>a;
    if(a>='A'&&a<='Z')
    {
        cout<<char(a+'a'-'A');
        return 0;
    }
    else if(a>='a'&&a<='z')
    {
        cout<<char(a+'A'-'a');
        return 0;
    }
    else
    {
        cout<<a;
        return 0;
    }
    return 0;
}