object Solution {

  def howManyGames(p: Int, d: Int, m: Int, s: Int): Int =  {
    var i =0
    var ss=s
    var sp=p
    while (ss >= sp){
      i=i+1
      ss = ss - sp
      sp = sp - d
      if (sp < m)
        sp=m
    }

    i
  }

    def main(args: Array[String]) {
        val sc = new java.util.Scanner (System.in);
        var p = sc.nextInt();
        var d = sc.nextInt();
        var m = sc.nextInt();
        var s = sc.nextInt();
        val answer = howManyGames(p, d, m, s);
        println(answer)
    }
}