#include<stdio.h>
#include<time.h>

using namespace std;

int main()
{

	long long p, i=0, n=0, k=0, ver;
	FILE *ifp, *ofp;
	ifp = fopen("fact.in", "r");
	ofp = fopen("fact.out", "w");
	
	fscanf(ifp, "%Ld", &p);
	
	
	for (i=1;i<=p;i++)
	{
		n=n+5;
		ver = -1;
		k=n;
		if (n/5 % 5 == 0)
			while(k%5==0 && k>0)
			{
				ver++;
				k=k/5;
			}
		else
			ver++;
		i = i+ver;
	}
	i--;
	
	if (p==0)
		fprintf(ofp, "%d", 1);
	else
		if (i>p)
			fprintf(ofp, "%d", -1);
		else
			fprintf(ofp, "%Ld", n);

	return 0;
}