Farmer John is standing in a rice field. He has a sunhat of radius ~K~, and any crops underneath the hat instantly die due to its sheer effectiveness. He walks around along in a circle along the circumference with radius ~N~. What is the area of crops that die?

Constraints

~1 \leq K,N \leq 10^6~

Input Specifications

The first and only line will contain space-separated integers ~K,N~.

Output Specifications

Output the area of crops that die. Any answer within ~10^{-6}~ will be considered correct.

Sample Input

3 5

Sample Output

188.495559215

Explanation for Sample Output

The region in which the crops die is ~\pi(8^2-2^2) = 60\pi~ and is shaded below. The blue region is the crops that die, and red is the hat size, and the middle circle is the path that farmer John walks along.