#include <stdio.h>

int main(){
  int w, h;
  long int n, k;
  long int end;

  scanf("%d%d%ld%ld", &h,&w,&n,&k);
  end = w * h % n;
  if(end == 0) end = n;

  if(k == end){
      printf("YES\n");
  }else{
      printf("NO\n");
  }
  return 0;
}