fun main(){
    var (hpOfTakahashi,attackOfTakahashi,hpOfAoki,attackOfAoki) = readLine()?.split(" ")!!.map { it.toInt() }
    var result = buttle(hpOfTakahashi,attackOfTakahashi,hpOfAoki,attackOfAoki)
    println(result)
}

fun buttle(hpOfTakahashi : Int,attackOfTakahashi : Int, hpOfAoki : Int,attackOfAoki :Int) : String{
    var turnOfTakahashi : Boolean = true
    var hpOfTakahashi = hpOfTakahashi
    var hpOfAoki = hpOfAoki
    while (hpOfTakahashi > 0 && hpOfAoki > 0){
        if (turnOfTakahashi){
            hpOfAoki -= attackOfTakahashi
            turnOfTakahashi = false
        }else{
            hpOfTakahashi -= attackOfAoki
            turnOfTakahashi = true
        }
    }
    if (hpOfTakahashi <= 0){
        return "No"
    }else{
        return "Yes"
    }
}
