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

Time Limit: 2 sec / Memory Limit: 1024 MB

﻿配点 : 100

### 制約

• 1 \leq R \leq 100
• 入力は全て整数である。

### 入力

R


### 入力例 1

1


### 出力例 1

6.28318530717958623200


10^{-2} 以下の絶対誤差・相対誤差が許容されるので、 6.28 も正解になりますが、6 は不正解となります。

### 入力例 2

73


### 出力例 2

458.67252742410977361942


Score : 100 points

### Problem Statement

Print the circumference of a circle of radius R.

### Constraints

• 1 \leq R \leq 100
• All values in input are integers.

### Input

Input is given from Standard Input in the following format:

R


### Output

Print the circumference of the circle. Your output is considered correct if and only if its absolute or relative error from our answer is at most 10^{-2}.

### Sample Input 1

1


### Sample Output 1

6.28318530717958623200


Since we accept an absolute or relative error of at most 10^{-2}, 6.28 is also an acceptable output, but 6 is not.

### Sample Input 2

73


### Sample Output 2

458.67252742410977361942