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