import java.util.Scanner

object Main extends App {
  val sc = new Scanner(System.in)
  val n, m, p, q = sc.nextInt
  val consumed = (1 to 12).map(i => if (i >= p && i < p + q) (2 * m) else (m)).toArray
  var nn = n
  var cnt = 0;
  while (nn > 0) {
    nn -= consumed(cnt % 12)
    cnt += 1
  }
  println(cnt)
}