'use strict'

function main (s) {
  let number = Number(s)
  if (number <= 0) {
    console.log(0)
    return
  }
  let quotient = Math.floor(number / 11)
  let remainder = Math.floor(number % 11)
  let few = remainder > 6 ? 2 : 1
  let count = quotient * 2 + few
  console.log(count)
}

function doMain () {
  let input = ''
  process.stdin.resume()
  process.stdin.setEncoding('utf8')
  process.stdin.on('data', (chunk) => {
    input += chunk
  })
  process.stdin.on('end', () => {
    input = input.trim()
    main(input)
  })
}

doMain()
