object Main extends App{
  val sc = new java.util.Scanner(System.in)
  var a, b, c, d = sc.nextInt()
  var i,j = 0
  while (a>0){
    i+=1
    a=a-d
  }
  while (c>0){
    j+=1
    c=c-b
  }
  printf(if(i>=j) "Yes" else "No")
}