#include <fstream>

using namespace std;

int main ()
{
	ifstream f("fact.in");
	ofstream g("fact.out");
	unsigned p, n=5, i=1, factorial=1, cifra=0;
	f>>p;
	if (!p)
		g<<1;
	else
	{
		do
		{
			factorial=1;
			for (;i<=n;i++)
				factorial*=i;
			while (factorial>9)
				if (factorial%10==0)
				{
					cifra++;
					factorial/=10;
				}
				else break;
			if (cifra==p)
				g<<n;
			else if (cifra>p)
				g<<-1;
			i=n+1;
			n+=5;
		} while (cifra<p);
	}

	return 0;
}