#include<bits/stdc++.h>
#define rep(i, n) for (int64_t i = 0; i < (int64_t)(n); i++)
#define all(v) v.begin(), v.end()
using ll = long long;
using namespace std;

int main(){
  ll x;cin>>x;
  cout<<x/11*2+(x%11>6?2:x%11>0?1:0);;
}
#include <bits/stdc++.h>
using namespace std;

int main(){
    long x, ans = 0;
    cin >> x;
    ans += 2 * (x / 11);
    x %= 11;
    if(x > 0) ans++;
    if(x > 6) ans++;
    cout << ans << endl;
    return 0;
}