#include<iostream>
#include <iomanip>
using namespace std;

void Nhapso(int& n)
{
	do
	{
		cout << "\nNhap n:";
		cin >> n;
		if ((n <= 10 || n >= 100) && (n % 2 == 0))
		{
			cout << "\nNhap lai!";
		}
	} while ((n <= 10 || n >= 100) || (n % 2 == 0));
}

int Giaithua(int n)
{
	int giaithua = 1;
	for (int i = 1; i <= n; i++)
	{
		giaithua *= i;
	}
	return giaithua;
}

float TinhF(int n)
{
	
	float tong = 0;
	for (int i = 1; i <= n; i++)
	{
		int phu = Giaithua(i);
		tong += (float)(1 + phu) / (i + n);
	}
	return tong;
}

int main()
{
	int n;
	Nhapso(n);
	float f = TinhF(n);
	cout <<fixed <<setprecision(2)<<f;

	cout << endl;
	system("pause");
	return 0;
}