#include<stdio.h>

using namespace std;
long v[100000000];
int main()
{
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	long int i=0,y,x;
	while(i<=100000000)
	{
		y=i/5;
		x=y;
		while(y>0)
		{
			y=y/5;
			x=x+y;
		}
		v[x]=i;
		i=i+5;
	}
	long int P;
	scanf("%ld",&P);
	if(v[P]!=0)printf("%ld",v[P]);
	else if(P==0)printf("0");
	else printf("-1");
	return 0;
}