#include<iostream>
#include<algorithm>
#include<vector>
#include<numeric>
#include<string>
#include<cmath>
#include<set>
#include<queue>
#include<deque>
#include<bitset>
#include<iomanip>
#include<cctype>
#include<map>
#include<cstring>
#include<bitset>
#include<cassert>

#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define rep2(i,a,b) for (int (i)=a;(i)<(b);(i)++)
#define all(x) (x).begin(),(x).end()

using namespace std;
using ll = long long int;

const int inf = 1001001000;
const long long int Inf = 1001001001001001000;



void print(vector<vector<int>> a){
	for (int i = 0; i < a.size(); i++)
	{
		for (int j=0;j<a[i].size();j++){
			cout << a[i][j] << " ";
		}
		cout << endl;
	}
}

void print(vector<vector<long long int>> a){
	for (int i=0;i<a.size();i++){
		for (int j=0;j<a[i].size();j++){
			cout << a[i][j] << " ";
		}
		cout << endl;
	}
}

void print(vector<int> a){
    int n = a.size();
    for (int j=0;j<n;j++) {
        if (j != n-1) cout << a[j] << " ";
        else cout << a[j] << endl;
    }
}

void print(vector<long long int> a){
    int n = a.size();
    for (int j=0;j<n;j++) {
        if (j != n-1) cout << a[j] << " ";
        else cout << a[j] << endl;
    }
}

void print(set<int> a){
	for (auto x:a)
		cout << x << " ";
	cout << endl;
}

//ワーシャルフロイト法のテンプレ.graphに最短経路が格納される.
//負の重みがある場合inf + const = inf に気を付けること.
//graphは隣接行列.
void WF(vector<vector<int>> &graph){
	int n = graph.size();
	for (int k = 0; k < n; k++){
		for (int i = 0; i < n; i++){
			for (int j = 0; j < n; j++){
				graph[i][j] = min(graph[i][j], graph[i][k] + graph[k][j]);
			}
		}
	}
}

//素因数分解をする関数.
map<long long int, int> prime_factorization(long long int a)
{
	map<long long int, int>ans;
	for (long long i = 2; i*i <= a; ++i) {
		while (a%i == 0) {
			ans[i]++;
			a /= i;
		}
	}
	if (a != 1)ans[a]++;
	return ans;
}

int main()
{
	ll x;
	cin >> x;
	ll ans = (x / 11) * 2;
	x = x % 11;
	if (x > 6)
		ans += 2;
	else if (x > 0)
		ans++;
	cout << ans << endl;

	return 0;
	
}
#include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#include<utility>
#include<map>
#include<set>
#include <sstream>
#include<queue>
#include<stack>
#include<functional>
#include<math.h>
#include <iomanip>
#include <numeric>
#include <iterator>
#include <math.h>
#include <list>
using namespace std;

int main(void){
  long x;
  cin >> x;
  long neko = x / 11;
  long amari = x % 11;
  cout << neko*2 + ((amari == 0) ? 0 :((amari > 6)? 2 : 1 ))<< endl;
  return 0;
}