open System
open System.Collections
open System.Collections.Generic
open System.IO
open System.Linq
open System.Net
open System.Security.Cryptography.X509Certificates

[<EntryPoint>]
let main _ = 
    let x = Console.ReadLine() |> int64
    let ans = 
        let a = (x / 11L) * 2L
        let b = 
            let t = x % 11L
            if   t =  0L then 0L
            elif t <= 6L then 1L
            else              2L
        a + b
    printfn "%i" ans
     
    0
    

