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 $10^{-6}$.

Sample Input 1

333

Sample Output 1

65287.907678222

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

Sample Input 2

634

Sample Output 2

90086.635834623

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