import java.util.Scanner;

class S27_massgame{
  public static void main(String[] args){
    int w, h;
    long n, k , end;
    Scanner sc = new Scanner(System.in);

    w = sc.nextInt();
    h = sc.nextInt();
    n = sc.nextLong();
    k = sc.nextLong();

    end = w * h % n;
    if(end == 0) end = n;
    if(k == end){
      System.out.println("YES");
    }else{
      System.out.println("NO");
    }

  }
}