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

int main()
{
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	scanf("%d",&p);
	if(!p) sol = 1;

	n = 1;
	while(s < p) s += n, n *= 5, k++;
	if(p > s-k && p < s) p = 0, sol = -1;

	while(p)
	{
        n = 1;

	    while(p-n >= 0)
	    {
	         p -= n;
	         n *= 5;
	    }

	    if(n == 1 && p) p = -1;
	    else sol += n;
	}

	printf("%d",sol);
	return 0;
}