#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>
typedef long long ll; 
using namespace std;

ll n, m; 

template < typename T >
inline T read()
{
	T x = 0, w = 1; char c = getchar();
	while(c < '0' || c > '9') { if(c == '-') w = -1; c = getchar(); }
	while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();
	return x * w; 
}

int main()
{
#ifndef ONLINE_JUDGE
	freopen("cpp.in", "r", stdin), freopen("cpp.out", "w", stdout);
#endif
	n = read <ll> (), m = n / 11 * 2ll, n %= 11;
	if(!n) { printf("%lld\n", m); return 0; }
	else if(n <= 6) { printf("%lld\n", m + 1); return 0; }
	else printf("%lld\n", m + 2); 
	return 0; 
}

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> P;
#define rep(i, n) for (ll i = 0; i < (int)(n); i++)
#define all(x) (x).begin(),(x).end()
#define m1(x) memset(x,-1,sizeof(x))
const int INF = 1e9 + 1;
const ll MOD = 1e9 + 7;
const double PI = 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799;


ll x;
ll ans;

int main(){
  cin >> x;
  ans = x / 11 * 2;
  if(x % 11 >= 7) ans+=2;
  else if(x%11 != 0) ans++;
  cout<<ans <<endl;
}