Circle Inside Circle

Time Limit: 1 sec

 

The Problem

A circle is drawn inside a circle. The radius of inner circle is r and outer circle R. What is the area of path between the circles?

Note: pi = 3.1416

 

 

 

 

The Input

Input file contains a series of line. Each line contains two integer numbers radius of inner circle r (r<=50) and radius of outer circle R (R<=50). Input is terminated by EOF.

 

The Output

For each line of input output will print the area of path, rounded to 2 decimal points in a separate line.

 

Sample Input

1 2

2 3

 

Sample Output

9.42

15.71

 

 

   

Problem Setter: Samia Safa Ahmed