#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
  #define _GLIBCXX_DEBUG
#else
  #define Debug(...) void(0)
#endif
using ll = long long;
#define rep(i, n) for (int i = 0; i < (n); ++i)

int main() {
  int x;
  cin >> x;
  int ans = 0, cnt = 0, now = 0;
  while (now != x) {
    switch (cnt % 7) {
      case 0:
      case 1:
      case 4:
        now += 2;
        ans += 2;
        break;
      default:
        now--;
        ans++;
    }
    cnt++;
  }
  cout << ans << endl;
  return 0;
}