fun main(args: Array<String>) {
  var x = readLine()!!.toLong()
  var count = x / 11 * 2
  val amari = x % 11

  if (amari == 0L) {
    // do nothing
  } else if (amari <= 6) {
    count += 1
  } else if (amari <= 11) {
    count += 2
  }
  println(count)
}