import java.util.*;
public class Masu {
	public static void main(String[] arg){
		Scanner sc = new Scanner(System.in);
		long h,w,n,k,sum,ch;
		h = sc.nextLong();
		w = sc.nextLong();
		n = sc.nextLong();
		k = sc.nextLong();
		sum = h*w;
		ch = sum % n;
		if((k == ch) || (k == n && ch == 0)){
			System.out.println("YES");
		}else {
			System.out.println("NO");
		}
	}
}