#include <stdio.h>

int main(){
  int A,B,C,D;
  scanf("%d %d %d %d", &A,&B,&C,&D);
  
  
  
  int turn = 1
  while(A > 0 && C > 0){
  
    if(turn == 1){
    
    C = C - B;
  }else if(turn == -1){  
   
    A = A - D;
  } 
  
  turn = -turn;
 }    
    
  if( A > 0 ){#include <stdio.h>

int main(){
    int A,B,X;
    scanf("%d %d %d",&A,&B,&X);
          
          
          
    if( A <= X && X <= A+B ){
      printf("YES\n");
    }else{
        printf("NO\n");
    }
    return 0;
}
      
      
      
    printf("Yes\n");
  }else{
    printf("No\n");
  }
  return 0;
}