#include <bits/stdc++.h>
//#include <atcoder/all>
//using namespace atcoder;
using namespace std;
using ll = long long;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
#define all(A) A.begin(),A.end()
#define rep(i, n) for (ll i = 0; i < (ll) (n); i++)

void chmin(ll& p, ll q) {
    p = min(p, q); return;
}

ll gcd(ll(a), ll(b)) {
    ll c = a;
    while (a % b != 0) {
        c = a % b;
        a = b;
        b = c;
    }
    return b;
}


int main() {
    //cin.tie(nullptr);
    //ios::sync_with_stdio(false);

    ll N;
    cin>>N;
    //N-=6;
    rep(i,1e7){
        if(i%7==6)N+=6;
        N--;
        if(N==0){
            cout<<i+1<<endl;
            return 0;
        }
    }
}