#include<bits/stdc++.h>
#define dbug printf("I am here\n");
#define Fast ios_base::sync_with_stdio(false); cin.tie(0);
#define vs            v.size()
#define ss            s.size()
#define sot(v)        sort(v.begin(),v.end())
#define rev(v)        reverse(v.begin(),v.end())
#define ii            pair<int, int>
#define int           long long
#define ull           unsigned long long
#define pb            push_back
#define mpp           make_pair
#define Okay          0
#define pi            3.14159

const int inf = 1e6;
const int cont = 1e18;
using namespace std;

void solve(){
    int n, ans;
    cin>>n;
    ans = n/11;
    bool f = 0;
    if(ans%2)f = 1;
    ans*=2;
    n%=11;
    if(f){
     if(n>5)ans+=2;
    else if(n) ans += 1;
    }
    else{
    if(n>6)ans+=2;
    else if(n) ans += 1;
    }
    cout<<ans<<endl;
}

int32_t main() {
   Fast;

   solve();
    return Okay;
}


#include <bits/stdc++.h>
using namespace std;

long long int MOD = 1000000007;

int main() {
  long long int X;
  cin >> X;
  if (X % 11 == 0) cout << X / 11 * 2 << endl;
  else if (X % 11 <= 6) cout << X / 11 * 2 + 1 << endl;
  else cout << X / 11 * 2 + 2 << endl;
}