#include "bits/stdc++.h"
using namespace std;
using ll = long long;
using Pii = pair<int, int>;
using Pll = pair<ll, ll>;
#define rep(i, begin, n) for (int i = begin; i < n; i++)
#define repe(i, begin, n) for (int i = begin; i <= n; i++)
#define repr(i, begin, n) for (int i = begin; i > begin - n; i--)
#define repre(i, begin, end) for (int i = begin; i >= end; i--)

template <class T>
inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}

template <class T>
inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}

const int inf = INT_MAX;
const int MOD = 1000000007;
const long long INF = LLONG_MAX;

// -------------------------------------------------------

ll x;

int main() {
  cin >> x;
  ll q = x / 11;
  ll r = x % 11;
  if (r == 0) {
    cout << q * 2;
    return 0;
  }

  if (1 <= r && r <= 6) {
    cout << q * 2 + 1;
    return 0;
  }

  cout << q * 2 + 2;
}

#include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
using namespace std;

long long int gcd(long long int a,long long int b){
    if(a%b==0){
        return b;
    }
    else{
        return gcd(b,a%b);
    }
}
long long int fac(long long int n){
    if(n==0){
        return 1;
    }
    else{
        return n*(fac(n-1))%1000000007;
    } 
}

int main(){
    long long int n,k,ans=0;
    cin>>n;
    ans+=2*((n-1)/11);
    if(n%11<7&&n%11>0){
        ans++;
    }
    else{
        ans++;
        ans++;
    }
    cout<<ans<<endl;
    return 0;
}