#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <map>
#include <stack>

using namespace std;

int main()
{
        string s;
        cin >> s;
        int cnt1 = 0;
        int cnt2 = 0;
        for (int i(0); i < s.size(); i++)
        {
                if (s[i] >= 'A' && s[i] <= 'Z')
                        cnt1++;
        }
        if (s[0] >= 'a' && s[0] <= 'z')
                cnt2 = 1;
        if ((cnt2 == 1 && cnt1 == s.size() - 1) || (cnt1 == s.size()) || (s.size() == 1))
        {
                for (int i(0); i < s.size(); i++){

                        if (s[i] >= 'A' && s[i] <= 'Z')
                                s[i] = s[i] - 'A' + 'a';
                        else
                        if (s[i] >= 'a' && s[i] <= 'z')
                                s[i] = s[i] - 'a' + 'A';
                }
                cout << s << endl;
        }
        else
                cout << s << endl;


        return 0;
}