#include<iostream.h>
#include<fstream.h>

int main()
{
	ifstream f;
	f.open("fact.in");
	ofstream g;
	g.open("fact.out");

	int l=0, p;
	
	f>>p;

	int aux,n,i;
	int ok=1;
	aux=5*p;
		i=aux;
	while (ok)
	{   n=0;
		aux=i;
		while(aux!=0)
		  {
			 aux/=5;
			 n=n+aux;
		  }
		if (n==p)  ok=0;
		else i-=5;
	}
	if (p==0) g<<"1";
	else if (n==p) g<<i;
	else g<<"-1";
	f.close();
	g.close();
	
			
	return 0;
}