#include <bits/stdc++.h>
using namespace std;
 
#define ll long long
#define ull unsigned long long
#define ld long double
 
void Free_palestine() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
}
 
const int N = 2e5 + 5;
const int MOD = 1e9 + 7;
const int MAXN = 1e5 + 5;


signed main(){
  Free_palestine();
  string st;
  cin >> st;

    bool flag = 1;
    for (int i = 1; i < st.size(); i++) {
        if (islower(st[i])) {
            flag = 0;
            break;
        }
    }

    
    if (flag) {
        for (int i = 0; i < st.size(); i++) {
            if (isupper(st[i])) {
                st[i] = tolower(st[i]);
            } else {
                st[i] = toupper(st[i]);
            }
        }
    }

    cout << st << "\n";
    return 0;
}