Score : $100$ points

Problem Statement

Assuming that the horizon seen from a place $x$ meters above the ground is $\sqrt{x(12800000+x)}$ meters away, find how many meters away the horizon seen from a place $H$ meters above the ground is.

Constraints

• $1 \leq H \leq 10^5$
• $H$ is an integer.

Input

Input is given from Standard Input in the following format:

$H$

Output

Print the answer. Your answer will be considered correct when the absolute or relative error from the judge's answer is at most $10^{-6}$.

333

65287.907678222

We have $\sqrt{333(12800000+333)} = 65287.9076782\ldots$. Outputs such as 65287.91 would also be accepted.

634

90086.635834623

We have $\sqrt{634(12800000+634)} = 90086.6358346\ldots$.