// 嘘二分探索
#include <iostream>
#include <vector>
using namespace std;

int solve(int N) {
    for (int day = 1;; ++day) {
        if (day % 7 == 0) N += 6;
        --N;
        if (N <= 0) return day;
    }
}

int uso_binary_search(int N) {
    int ng = 0, ok = 13964;
    while (ok > ng + 1) {
        int c = (ok + ng) / 2;
        int num_problem = N + c / 7 * 6;
        (num_problem <= c ? ok : ng) = c;
    }
    return ok;
}

int main() {
    int N;
    cin >> N;
    cout << uso_binary_search(N) << '\n';
}