337 - Circumference

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