#include "pch.h"
#include <iostream>
using namespace std;
int fact(int k)
{
	if (k == 0 || k == 1)
		return 1;
	return k * fact(k - 1);
}
void main()
{
	int k = 1;
	double s = 0, eps;
	cin >> eps;
	while (eps >= (double)fact(k) / fact(5 + k - 1));
	{
		s += (double)fact(k) / fact(5 + k - 1);
		k++;
	}
	cout << s;
}