ll tilings1(int n, int m) {
    n = (n & 1) ? (n + 1) >> 1 : n >> 1;
    m = (m & 1) ? (m + 1) >> 1 : m >> 1;
    ld ans = 1.0;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            ans *= 4 * (cos(PI * i / (n + 1)) * cos(PI * i / (n + 1)) + cos(PI * j / (m + 1)) * cos(PI * j / (m + 1)));
        }
    }
    return llround(ans);
}