use std::io;

fn main() {
    let mut input = String::new();
    io::stdin().read_line(&mut input)
        .expect("Read Error");
    let numbers: Vec<i64> = input.split_whitespace()
        .map(|w| w.parse().unwrap())
        .collect();

    println!("{}", solve(numbers[0],  numbers[1], numbers[2], numbers[3]));
}

fn solve(a: i64, b: i64, c: i64, d: i64) -> i64 {
    a * b * c % d
}

#[test]
fn it_works() {
    assert_eq!(2, solve(1,2,3,4));
    assert_eq!(0, solve(2,2,2,2));
}