#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
const int maxn=100000;
typedef long long ll;
ll  x;
ll cheng_fast(ll a,ll b){
	ll an=0;
	for(;b;b>>=1,a+=a)
	  if(b&1)an+=a;
	return an;
}
int main(){
	scanf("%lld",&x);
	ll  y=x/11,ans;
	ll  w=x-y*11;
	if(w==0)cout<<y*2<<endl;
	else if(w<=6){
		ans=(y<<1)+1;
		cout<<ans<<endl;
	}
	else {
		ans=(y<<1)+2;cout<<ans<<endl;
	}
	return 0;
}