#include <stdio.h>
int main()
{
	long long ad,c,nr,n,i,j,p;
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	scanf("%lld",&p);
	c=p;
	if (p==0)
	{
		printf("1\n");
		return 0;
	}
	while (c%5==0)
		c=c/5;
	if (c==1)
	{
		printf("-1");
		return 0;
	}

	n=0;
	nr=0;
	ad=0;
	while (nr+156<p)
	{
		n=n+625;
		nr=nr+156;
		if (nr%625==0)
			ad=nr/625;

	}
	
	while (nr<p) 
	{
		n=n+5;
		c=n;
		while (c%5==0)
		{
			c=c/5;
			nr++;		
		}	
	}
	printf("%lld\n",n);	
	
	return 0;
}