#include <fstream>

#define I_F "xcoins.in"
#define O_F "xcoins.out"

using namespace std;

long long n;
const int fuckdonny[21]={0,0,0,0,0,0,6,3,4,3,2,3,4,3,4,3,4,5,4,5,4};

void Input();
void Output();

int main()
{
	Input();
	Output();
	return 0;
}

void Input()
{
	ifstream fin(I_F);
	fin>>n;
	fin.close();
}

void Output()
{
	ofstream fout(O_F);
	if (n<=20)
		fout<<fuckdonny[n]<<endl;
	else
		if (n%5==0)
			fout<<n/5<<endl;
		else
			fout<<n/5+(((n%5)%2==0)2:3)<<endl;
	fout.close();
}