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

int main() {
    ll x; cin >> x;
    ll nokori = x % 11;
    ll ans = (x-nokori) / 11;
    ans *= 2;
    if(nokori > 6){
        ans += 2;
    } else if(nokori > 0) {
        ans++;
    }

    cout << ans << endl;

    return 0;
}
#include <bits/stdc++.h>
#define ALL(A) (A).begin(), (A).end()
#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)

using namespace std;

const ll mod = 1e9 + 7;
const ll INF = -1 * ((1LL << 63) + 1);
const int inf = -1 * ((1 << 31) + 1);

int main(void){
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);
    string s;
    cin >> s;
    rep(i,s.size()-8){
        cout << s[i];
    }
}