#include <iostream>

using namespace std;

int main()
{
    string str;
    cin>>str;
    bool firstLetter; // true for lower.
                    // false for upperCase.
    bool otherLetters = true;
    ///validation.
    for(int i =0; i<str.size();i++) {
        if(i == 0){
            //pirveli simbolo
            if(str[i]>='a' && str[i]<='z'){
                firstLetter = true;
            }else firstLetter = false;
        }else{
            //danarcheni
            if(str[i] <'A' || str[i]>'Z') {
                otherLetters = false;
            }
        }
    }
    //1) firstLetter == true    da  otherLetters = true;
    //2) firstLetter == false   da  otherLetters = true;
    if((firstLetter && otherLetters)
    || (!firstLetter && otherLetters)) {
        //shecvla
        for(int i =0; i<str.size();i++) {
            if(str[i]>='A' && str[i] <='Z') {
                str[i] += 'a' - 'A';
            }
        }
        if(firstLetter && otherLetters){
            str[0] += 'A' -'a';
        }
        cout << str << endl;
    }else{
        cout << str << endl;
    }



    return 0;
}