#include<bits/stdc++.h>

using namespace std;

int isCapsOn(string s){
    for(int i = 1; i<s.size(); i++){
        if(islower(s[i])){
            return 0;
        }
    }

    return 1;
}


int main(){

    string sinp;
    cin >> sinp;

    if(isCapsOn(sinp)){

        for(int i = 0; i<sinp.size(); i++){

            if( islower(sinp[i]) )
                sinp[i] = toupper(sinp[i]);

            else
                sinp[i] = tolower(sinp[i]);
        }

        cout << sinp << endl;
    }
    else
        cout << sinp << endl;

    return 0;
}