fun main(args: Array<String>) {
    // A B C D
    val list = nextIntList()
    // hp
    var tH = list[0]
    var aH = list[2]
    // attack
    val tA = list[1]
    val aA = list[3]


    val stop = true
    var res = ""
    while(stop){
        // t->a
        aH = j(tA,aH)
        if(aH < 1){
            res = "Yes"
            break
        }
        tH = j(aA,tH)
        if(tH < 1){
            res = "No"
            break
        }
    }
    println(res)
}
fun nextIntList() = next().split(" ").map{ it.toInt() }
fun next() = readLine()!!


fun j(a:Int, h:Int):Int{
    return h-a
}
