import 'dart:io';

void main(List<String> args) {
  List<String> input = stdin.readLineSync().split(" ");
  int a = int.parse(input[0]);
  int b = int.parse(input[1]);
  int c = int.parse(input[2]);
  int d = int.parse(input[3]);
  
  while(a != 0) {
  	a = a - d;
    b = b - c;
    if(a = 0) {
      print('No');
    } else {
      print('Yes');
    }
  }
}