#include <bits/stdc++.h>
using namespace std;
const int MM = 1e9 + 7;
const double eps = 1e-8;
const int MAXN = 2e6 + 10;
int n, m;
void prework() {}
void read() {}
void solve(int casi) {
  long long x;
  cin >> x;
  long long y = x / 11;
  y *= 2;
  x %= 11;
  if (x == 0)
    ;
  else if (x <= 6)
    y++;
  else
    y += 2;
  cout << y << endl;
}
void printans() {}
int main() {
  prework();
  int T = 1;
  for (int i = 1; i <= T; i++) {
    read();
    solve(i);
    printans();
  }
  return 0;
}
