#include<fstream>
using namespace std;

int main()
{
	int p,n=0,m,i,k=0;

	fstream f ("fact.in", ios::in);
	fstream g ("fact.out", ios::out);

	f>>p;

	if (p==0)
		g<<1;
	else
	{
		while (k < p)
		{
			n = n+5;
			m=n;

			i=0;
			while (m%5==0)
				m=m/5, i++;

			k = k+i;
		}

		g<<n;
	}

	return 0;
}