101630: [AtCoder]ABC163 A - Circle Pond

Memory Limit:256 MB Time Limit:2 S
Judge Style:Text Compare Creator:
Submit:0 Solved:0

Description

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

Input

题意翻译

求半径为 $r$ 的一个圆的周长

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