Contest Duration: - (local time) (100 minutes) Back to Home
A - Horizon /

Time Limit: 2 sec / Memory Limit: 1024 MB

### 制約

• 1 \leq H \leq 10^5
• H は整数である

### 入力

H


### 出力

なお、想定解との絶対誤差または相対誤差が 10^{-6} 以下であれば、正解として扱われる。

### 入力例 1

333


### 出力例 1

65287.907678222


\sqrt{333(12800000+333)} = 65287.9076782\ldots です。65287.91 などの出力でも正解となります。

### 入力例 2

634


### 出力例 2

90086.635834623


\sqrt{634(12800000+634)} = 90086.6358346\ldots です。

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

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.