fun main() {
    val i = readLine()!!.split(" ").map(String::toInt)
    var T_HP  = i[0]
    val T_ATK = i[1]
    var A_HP  = i[2]
    val A_ATK = i[3]
    // T > A > T > A
    var t = 0
    while (/*T_HP <= 0 || A_HP <= 0*/ true) {
        if (t % 2 == 0) { // Takahashi
            A_HP -= T_ATK
            if (A_HP <= 0) {
                println("Yes")
                break
            }
        } else { // Aoki
            T_HP -= A_ATK
            if (T_HP <= 0) {
                println("No")
                break
            }
        }
        ++t
    }
}