#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
using pii = pair<int, int>;

int main() {
  ll n;
  cin >> n;
  ll m = max(0LL, n - 3);
  ll ans = 5 * m;
  ans += min(n, 3LL);
  cout << ans << endl;
  return 0;
}