#include<iostream>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#include<cstring>
#include<string>

using namespace std;

const int aa[21]={0,0,0,0,0,1,6,3,4,3,2,3,4,3,4,3,4,5,4,5,4};

long long n,ans;

int main()

{
	freopen("xcoins.in","r",stdin);
	freopen("xcoins.out","w",stdout);
	cin>>n;
	if(n<=20)
	{
		ans=aa[n];
		cout<<ans<<endl;
		return 0;
	}
	if(n%5==0)
	{
		ans=n/5;
		cout<<ans<<endl;
		return 0;
	}
	if((n%5)%2==1)
	{
		ans=n/5+3;
		cout<<ans<<endl;
	}
	else
	{
		ans=n/5+2;
		cout<<ans<<endl;
	}
	return 0;
}