#include <fstream>
#include <iostream>
using namespace std;
	ifstream fin("fact.in");
ofstream fout("fact.out");
int main ()
{
	unsigned long long p,n,aux,nr,i,fact=0;

	fin>>p;
	n=0;
	for (i=5;fact<p;i+=5)
	{
		aux=i;
		n=i/5;
		fact++;
		while (n%5==0)
		{
			fact=fact+1;
			n=n/5;
		}
	}
	
	if (fact==p)
		fout<<i-5;
	else
		fout<<-1;
	fin.close ();
	fout.close ();
	return 0;
}