import java.util.*

fun main(args: Array<String>) {
  val sc = Scanner(System.`in`)
  val x = sc.nextLong()


  var count = x / 11L * 2L
  val last = x % 11L
  if (last > 6) {
    count += 2L
  } else if (last > 0) {
    count += 1L
  }


  println(count)

}
