fun main(args: Array<String>) {
    val (N, M, P, Q) = readLine()!!.split(" ").map { it.toInt() }
    var n = N
    var m = 1

    for (i in 1..Int.MAX_VALUE) {
        if (m in P until P + Q) {
            n -= M
        }
        n -= M

        m += 1
        if (m > 12) {
            m = 1
        }

        if (n <= 0) {
            println(i)
            break
        }
    }
}