fun main(args: Array<String>) {
    val (A, B, C, D) = readLine()!!.split(" ").map { it.toInt() }

    var takahashi = A to B
    var aoki = C to D

    while (true) {
        aoki = (aoki.first - takahashi.second) to aoki.second
        if (aoki.first <= 0){
            println("Yes")
            break
        }

        takahashi = (takahashi.first - aoki.second) to takahashi.second
        if (takahashi.first <= 0){
            println("No")
            break
        }
    }
}