import scala.util.control.Breaks._

object Main extends App {
  var x = scala.io.StdIn.readLong()
  var time = x / 11

  breakable {
    if (x <= 6) {
      println(1)
      break()
    }
    if (x <= 11) {
      println(2)
      break()
    }

    if (x % 11 == 0){
      println(time * 2)
    } else if (x % 11 <= 6) {
      println(time * 2 + 1)
    } else {
      println(time * 2 + 2)
    }


  }
}
