Vitya loves educational TV channels. Having seen a program on ancient handicrafts, he decided to apply himself to pottery. As the first task, he built a potter's wheel from an old bucket and acquired a small straight stick for smoothing out the walls of the vessels. He plans to use the kitchen oven for firing his creations... So far Vitya manages to produce only beakers---vessels having the shape of a truncated cone with the radius of the base equal to the radius of the bottom of the bucket and the length of the side equal to the length of his smoothing stick. Vitya wants to give his first proper beaker to his mother as her birthday present. He also wants the vessel to be able to contain as much delicious foods as possible and thus he asks you to compute the maximal volume possible with his technology. \InputFile The only input line contains two integers \textbf{L} and \textbf{D} (\textbf{1} ≤ \textbf{L}, \textbf{D} ≤ \textbf{10^3}), the length of the stick and the diameter of the bucket. Thickness of the walls of the beaker is negligible. \OutputFile The only output line should contain the desired volume where either absolute or relative deviation from the true value is at most \textbf{10^\{ - 9\}}.