//Roberto Deresu - FMI
//Re :)
#include<cstdio>
int p,n,nr;
using namespace std;

int main()
{
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	scanf("%d",&p);

	if(!p) n = 1;
	else
	{
	    n = 1;
	    while(p-n >= 0)
	    {
	         p -= n;
	         n *= 5;
	    }

	    if(n == 1) n = 0;
	    while( p > 0)
        {
            n += 5;
            nr = n;
            while(!(nr%5)) nr /= 5, p--;
        }
	}

	if(p >= 0) printf("%d",n);
	else printf("-1");
	return 0;
}