#include<iostream>
using namespace std;
typedef long long ll;
int main(){
    ll n;
    while(cin>>n){
        ll ans,x;
        ans=n/11<<1;
        x=n%11;
        if(x>6)
            ans+=2;
        else if(x)
            ans++;
        cout<<ans<<endl;
    }
    return 0;
}

#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define printVec(v) printf("{"); for (const auto& i : v) { std::cout << i << ", "; } printf("}\n");
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; }
using namespace std;
using P = pair<int,int>;
using ll = long long;
const ll INF = 1LL<<60;
const double PI = 3.1415926535897932;
const int MOD = 1e9 + 7;

//cin.tie(0);ios::sync_with_stdio(false);
int main() {
  ll x;
  cin >> x;

  ll ans = x / 11 * 2;
  x %= 11;

  if (x != 0) {
    if (x <= 6) {
      ans += 1;
    } else {
      ans += 2;
    }
  }

  cout << ans << endl;
  return 0;
}
