Given a positive integer \(n\), compute the harmonic sum

\(H(n) = 1 + \frac{1}{2} + \frac{1}{3} + \cdots + \frac{1}{n}\).

Input

One line containing \(n\).

The input satisfies:

• \(1 \le n \le 10^6\)

Output

Print \(H(n)\), rounded to exactly three digits after the decimal point.

Example

Input

2

Output

1.500

Explanation

H(2) = 1 + 1/2 = 1.5, printed with exactly three decimal places as 1.500.