#include<stdio.h>
using namespace std;
int cont;
int nrdiv(int x)
{
	while((x!=1) && (x%5==0))
	{
		x=x/5;
	    cont++;
	}
}
int main()
{
	int p,i,z;
	z=-1;
	i=0;
	cont=0;
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	scanf("%d",&p);
	if(p<=0)
		printf("%d",z);
	else
	{
		while(cont!=p)
		{
		i=i+5;
		nrdiv(i);
		}
		printf("%d",i);
	}
	fclose(stdin);
	fclose(stdout);
	return 0;
}