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