fun main(args: Array<String>) {
    val line = readLine()!!.trim()
    var (takahasi_hp: Int, takahasi_attack: Int, aoki_hp: Int, aoki_attack: Int) = line.split(" ").map {it.toInt()}

    while (true) {
        aoki_hp -= takahasi_attack
        if (aoki_hp <= 0) {
            println("Yes")
            break
        }

        takahasi_hp -= aoki_attack
        if (takahasi_hp <= 0) {
            println("No")
            break
        }
    }
}