#include<bits/stdc++.h>
using namespace std;
int main(){
	long long n,nam=0,wac=0;
	cin>>n;
	int wc=n;
	if(wc/11<1&&wc/5<1){
		cout<<n;
		return 0;
	}else{
		wac=wc/5;
		wc=wc%5;
		wac+=wc;
		int wc=n;
		nam=wc/11;
		wc=wc%11;
		if(wc<5){
			nam+=wc;
		}else{
			nam+=wc/5;
			wc=wc%5;
			nam+=wc;
		}
    }
    if(nam<wac){
    	cout<<nam;
	}else{
		cout<<wac;
	}
	return 0;
}