fn main() {
    let mut temp = String::new();
    std::io::stdin().read_line(&mut temp).ok();
    let temp: Vec<usize> = temp.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let l = temp[0];
    let r = temp[1];
    let m = temp[2];
    let k = temp[3];

    let start = l * k % m;
    let diff = ((r - l) * k).min(m);
    let end = start + diff;
    if start == 0 || m <= end {
        println!("Yes");
    } else {
        println!("No");
    }
}