Description

After paying, Yue Luo Wu Ti thought, "You ripped me off!" So when Ai Yu Chou asked how much it cost, Yue Luo Wu Ti replied with a bunch of gibberish. Ai Yu Chou said, "Forget it, I only ask: what is the price of the $n$-th dish?" Yue Luo Wu Ti wrote:

$$F_n=\dfrac{\left(\frac{1+\sqrt{5}}{2}\right)^n-\left(\frac{1-\sqrt{5}}{2}\right)^n}{\sqrt{5}}$$

Since Ai Yu Chou had studied programming, he computed $F_n$ in $1$ minute. Yue Luo Wu Ti was shocked. Can you, like Ai Yu Chou, compute the value of $F_n$?

Input Format

One line containing a non-negative integer $n$.

Output Format

One line containing a real number $F_n$, with two decimal places.

6

8.00

Hint

For all testdata: $0 \leq n \leq 48$.

Translated by ChatGPT 5