#include <stdio.h>
 
int main(){
 int A,B,C,D;
  scanf("%d %d %d %d",&A,&B,&C,&D);
  
  while(A-D > 0 && C-B > 0){
  int E,F;
    E = C - B;
    F = A - D;
    C = E;
    A = F;
  }
  
  if ( C - B <= 0){
  printf("Yes");
  }
  
  else if ( A - D <= 0){
  printf("No");
  }
}