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

typedef long long ll;
typedef long double ld;
typedef pair<int,int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;

#define f first
#define s second
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define pb push_back

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b); i >= (a); i--)
#define R0F(i, a) ROF(i, 0, a-1)
#define trav(x, a) for (auto& x: a)

const int MX  = 2e5+5;
const int MOD = 1e9+7;
const ll  INF = 1061109567; // 4557430888798830399LL
const ld  EPS = 1e-9;
const ld  PI  = acos(-1);

int main() {

    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    ll x; cin >> x;

    if (x%11 == 0) {
        cout << x/11*2 << "\n";
    } else if (x%11 <= 6) {
        cout << x/11*2+1 << "\n";
    } else {
        cout << x/11*2+2 << "\n";
    }

}

#include <bits/stdc++.h>
using namespace std;
#define _GLIBCXX_DEBUG //GCC5.4.1で配列の範囲外アクセスをエラーにする

//cmdで g++ test.cpp とするとコンパイルできる
//制限1秒なら10^6は余裕 10^7は多分間に合う 10^8はよほど単純でないと厳しい
// https://github.com/atcoder/live_library
// cppdbg: test.exeのterminalに標準入力を打てる

#define ALL(x) x.begin(),x.end()
#define get_tp(t,i) get<i>(t)
#define len(x) (ll)(x.size())
#define ub(a,x) (upper_bound(ALL(a),x)-a.begin())
#define lb(a,x) (lower_bound(ALL(a),x)-a.begin())
typedef long long ll; //long long
typedef pair<int,int> pii; //pair<int,int>
typedef pair<long long,long long> pllll; //pair<ll,ll>
typedef vector<int> vi; //vector<int>
typedef vector<vector<int>> vvi; //vector<vector<int>>
typedef vector<ll> vll; //vector<long long>
typedef vector<vector<ll>> vvll; //vector<vector<long long>>
typedef priority_queue<ll, vector<ll>, greater<ll> > gpq; //逆順priority_queue
typedef priority_queue<ll> pq;

//const int MOD=998244353;
const int MOD=1000000007; //10^9+7
const long double PI=3.1415926535897932;

int main(){
    ll x;cin>>x;
    ll ans=0;
    ans+=x/11;
    x-=ans*11;
    ans*=2;
    if(x>0){ans+=(x<=6)?1:2;}
    cout<<ans<<endl;
}