#include <fstream>
#include <limits>
using namespace std;

long fact(long a);

int main()
{
	long a;
	ifstream in("fact.in");
	in>>a;
	in.close();
	ofstream out("fact.out");
	out<<fact(a)<<"\n";
	out.close();
	return 0;
}


long fact(long a)
{	
	if (a==0) return 1;
	int rez=1,nr=5;
	while(true)
	{
		if (rez==a)
		{
			break;
		}
		else if (rez>a)
		{
			return -1;
		}
		else
		{
			nr+=5;
			int c=nr;
			while (c%5==0)
			{
				c/=5;
				++rez;
			}
		}
	}
	return nr;
}