object Solution {
  val sc = new java.util.Scanner(System.in)

  def main(args: Array[String]) : Unit = {
    var cost = sc.nextInt

    val delta = sc.nextInt
    val min = sc.nextInt

    var money = sc.nextInt

    var bought = 0

    while (cost > min && money >= cost) {
      bought += 1
      money -= cost
      cost -= delta
    }

    if (cost <= min) {
      cost = min
      bought += money / cost
    }

    println(bought)
  }
}