fn min(a: int, b: int): int {
    return a < b ? a : b;
}

fn max(a: int, b: int): int {
    return a > b ? a : b;
}

fn sign(a: int): int {
    return a > 0 ? 1 : a < 0 ? -1 : 0;
}

fn abs(a: int): int {
    return a * sign(a);
}

fn factorial(n: int): int {
    let res: int = 1;
    for (;n > 0; n = n - 1)
        res = res * n;
    return res;
}