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

int main(){
  int i,j,cnt;
  ll x;
  cin>>x;
  if(x%11==0)cout<<(x/11)*2;
  else if(x%11>6)cout<<2+(x/11)*2;
  else if(x%11<=6)cout<<1+(x/11)*2;
}