131A. cAPS lOCK.cpp

#include <algorithm>
#include <cmath>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <set>
#include <string>
#include <vector>
using namespace std;

using ll = long long;
using ld = long double;
using str = string;

using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define mp make_pair
#define f first
#define s second

using vi = vector<int>;
using vl = vector<ll>;
using vd = vector<ld>;
using vs = vector<str>;
using vc = vector<char>;

#define sz(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define pb push_back
#define eb emplace_back

const int mod = 998244353; // 1e9+7;

void solve()
{
    str s;
    cin >> s;

    int chk = 1;
    for (int i = 1; i < sz(s); i++)
        if (islower(s[i]))
            chk = 0;

    if (chk == 1)
    {
        char c;
        for (int i = 0; i < sz(s); i++)
        {
            if (islower(s[i]))
                c = toupper(s[i]);
            else
                c = tolower(s[i]);
            cout << c;
        }
    }

    else
        cout << s;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int tc = 1;
    // cin >> tc;

    while (tc--)
        solve();

    return 0;
}