#include <iostream>
using namespace std;
int main() {
    char a;
    cin>>a;
    if(a>='a'&&a<='z')
    {
        a=a-32;
        cout<<a;
    }
    else if (a>='A'&&a<='Z')
    {
        a=a+32;
        cout<<a;
    }
    else 
        cout<<"输入错误，请输入字符"<<endl;
    return 0;
}