import java.util.Scanner;
public class No166 {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		long h = s.nextLong() , w = s.nextLong() , n = s.nextLong() , k = s.nextLong();
		s.close();

		if(h * w % n == k % n){
			System.out.println("YES");
		}else{
			System.out.println("NO");
		}

	}

}