Circumference

Time Limit: 1 sec

 

The Problem

Radius of a Circle, R is given. What will be the Circumference of the Circle?

Note : The Circumference of a Circle is 2 * pi * radius [pi = 3.1416]

 

The Input

The input file contains a series of line. Each line contains a single integer Radius R (R <= 100). Input is terminated by EOF.

 

The Output

The output will show the Circumference of the Circle rounded to 2 decimal points in a separate line.

 

Sample Input

2

5

 

Sample Output

12.57

31.42

 

 

 

 

Problem Setter: Samia Safa Ahmed