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

int main()
{
    long long a;
    cin >> a;
    long long ls = a / 11;
    if (ls * 11 == a)
        cout << ls*2;
    else
        cout << ls*2+1;
    return 0;
}
