import io.StdIn._

object Main extends App {
  val arr       = readLine.split(" ")
  val tHitPoint = arr(0).toInt
  val tAttack   = arr(1).toInt
  val aHitPoint = arr(2).toInt
  val aAttack   = arr(3).toInt

  def process(tHitPointRest: Int, aHitPointRest: Int, isTsTurn: Boolean): Unit = {
    if (isTsTurn) {
      if ((aHitPointRest - tAttack) > 0) process(tHitPointRest, aHitPointRest - tAttack, !isTsTurn)
      else print("Yes")
    } else {
      if ((tHitPointRest - aAttack) > 0) process(tHitPointRest - aAttack, aHitPointRest, !isTsTurn)
      else print("No")
    }
  }

  process(tHitPoint, aHitPoint, true)
}
