fn main() {
    let mut input = String::new();
    std::io::stdin().read_line(&mut input).ok();
    let input: Vec<u64> = input
        .split_whitespace()
        .map(|n| n.parse().unwrap())
        .collect();

    if (input[0] * input[1]) % input[2] == input[3] % input[2] {
        println!("YES");
    } else {
        println!("NO");
    }
}