#include <bits/stdc++.h>
using namespace std;

#ifdef _RUTHEN
#include "debug.hpp"
#else
#define show(...) true
#endif

using ll = long long;
#define rep(i, n) for (int i = 0; i < (n); i++)
template <class T> using V = vector<T>;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int N;
    cin >> N;
    int cnt = 0;
    for (int i = 1; i <= 14000; i++) {
        if (i % 7 == 0) {
            N += 6;
        }
        cnt++;
        if (N == cnt) {
            cout << i << '\n';
            return 0;
        }
    }
    return 0;
}