#include <cstdio>
#define ui unsigned int
int main()
{
	ui cnt, n, i, p, q;
	
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	scanf("%d", &n);
	
	i=(1<<31);
	for(cnt=(1<<30);cnt;cnt>>=1)
		if(i-cnt>=1)
		{
			q=0;
			p=i-cnt;
			while(p)q+=p/5, p/=5;
			if(q>=n) i-=cnt;
		}
	
	q=0;
	p=i;
	while(p)q+=p/5, p/=5;
	if(q==n) printf("%d\n", i);
		else printf("-1\n");
	return 0;
}