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

typedef long long ll;
typedef long double ld;
typedef vector<vector<int>> Graph;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
#define pi 3.14159265359
#define inf 2147483647
#define INF 9223372036854775807
#define mod 1000000007
#define mod2 998244353

int main() {
	ll x; cin >> x;
	ll n = x / 11;
	ll ans = 2 * n + ((x - 11 * n) + 5) / 6;
	cout << ans << endl;
	return 0;
}
#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#define ll long long
using namespace std;
int main(){
    ll x;
    cin>>x;
    ll d=x/11;
    ll r=x%11;
    if(0==r){
        cout<<2*d<<endl;
    }else{
        if(r<7){
            cout<<2*d+1ll<<endl;
        }else{
            cout<<2*d+2ll<<endl;
        }
    }
    return 0;
}