#include <bits/stdc++.h>
using namespace std;
int main() {
  int x;
  cin >> x;
  vector<int> a =  {2,2,-1,-1,2,-1,-1};
  int now = 0;
  int ans = 0;
  int i = 0;
  while (true) {
    now += a[i];
    ans += abs(a[i]);
    if (now == x) break;
    i = (i + 1) % 7;
  }
  cout << ans << endl;
  return 0;
}