fn main() {
    let stdin = std::io::read_to_string(std::io::stdin()).unwrap();
    let mut stdin = stdin.split_ascii_whitespace();

    let a: u32 = stdin.next().unwrap().parse().unwrap();
    let b: u32 = stdin.next().unwrap().parse().unwrap();
    let c: u32 = stdin.next().unwrap().parse().unwrap();
    let d: u32 = stdin.next().unwrap().parse().unwrap();

    println!("{}", output(solve(a, b, c, d)));
}

fn solve(a: u32, b: u32, c: u32, d: u32) -> u32 {
    (a as u64 * b as u64 % d as u64 * c as u64 % d as u64) as u32
}

fn output(ans: u32) -> u32 {
    ans
}