#include<fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
long i,j,n,m,k,s,t,r,p,val;
long cauta(long x,long y)
{
	long a;
	m=((x+y)/2)*5;
	r=5;
	k=0;
	while(m>=r)
	{
		k+=m/r;
		r*=5;
	}
	a=-1;
	if(k<val)
	{
		if(x!=m/5)
		{
			a=cauta(m/5,y);
		}
	}
	if(k>val)
		if(m/5!=y)
			a=cauta(x,m/5);
	if(k==val)
		a=m;
	return a;
}
int main()
{
	f>>val;
	n=cauta(0,2000000000);
	if(n==-1)
		g<<-1;
	else
		n=(n/5)*5;
	if(n==0)
		g<<1;
	if(n>0)
		g<<n;
return 0;
}