import java.util.Scanner

object Main {
  def main(args: Array[String]): Unit = {
    //nextLineとnextを同時に使ったら死ぬ
    val sc = new Scanner(System.in)
    val x = sc.nextLong()

    val d = x / 11
    val m = x % 11

    val tmp = if (m > 6) 2 else 1

    println(d * 2 + tmp)
  }

  def debug(args: Any*): Unit = {
    Console.err.println(args.mkString(" "))
  }
}
