fn main() {
    let mut xx = String::new();
    std::io::Read::read_to_string(&mut std::io::stdin(), &mut xx).ok();
    let xx: Vec<f64> = xx.split_whitespace().flat_map(str::parse).collect();

    let time_x: Vec<f64> = xx[3..].iter().map(|&d| d / xx[0]).collect();
    let time_y: Vec<f64> = xx[3..].iter().map(|&d| d / xx[1]).collect();

    for i in 0..(time_x.len() - 1) {
        if time_y[i + 1] < time_x[i] {
            println!("NO");
            return;
        }
    }

    println!("YES");
}