char change_register(char c) {
    if (c >= 'a' && c <= 'z') {
        c = c - 'a' + 'A';
        return c;
    }
    if (c >= 'A' && c <= 'Z') {
        c = c - 'A' + 'a';
        return c;
    }
    return c;
}

int task3() {
    char c;
    cin >> c;
    c = change_register(c);
    cout << c;
    return 0;
}