#include <iostream>
#include <fstream>
using namespace std;
 
int main()
{

	
	int nr,i;
	unsigned long int n,p,aux;
	ifstream f("fact.in");
	ofstream g("fact.out");
	f>>p;
	n=0;
	for(i=1;i<=p;i++)
	{	nr=0;
		n=n+5;
		aux=n/5;
		while(aux%5==0)
		{	nr++;
			aux=aux/5;
		}
		i=i+nr;
	}
	if(i>p+1)
	{	g<<-1;
		return 0;
	}
	if(p==0)
	{	g<<1;
		return 0;
	}
	g<<n;
	f.close();
	g.close();

  
}