B"One beautiful day Vasily the bear painted 2m circles of the same radius R on a coordinate plane. Circles with numbers from 1 to m had centers at points (2R xe2 x80 x89- xe2 x80 x89R, xe2 x80 x890), (4R xe2 x80 x89- xe2 x80 x89R, xe2 x80 x890), ..., (2Rm xe2 x80 x89- xe2 x80 x89R, xe2 x80 x890), respectively. Circles with numbers from m xe2 x80 x89+ xe2 x80 x891 to 2m had centers at points (2R xe2 x80 x89- xe2 x80 x89R, xe2 x80 x892R), (4R xe2 x80 x89- xe2 x80 x89R, xe2 x80 x892R), ..., (2Rm xe2 x80 x89- xe2 x80 x89R, xe2 x80 x892R), respectively. Naturally, the bear painted the circles for a simple experiment with a fly. The experiment continued for m2 days. Each day of the experiment got its own unique number from 0 to m2 xe2 x80 x89- xe2 x80 x891, inclusive. On the day number i the following things happened: Help Vasily, count the average distance the fly went along the coordinate plane during each of these m2 days. The first line contains two integers m, xe2 x80 x89R (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89m xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89105, 1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89R xe2 x80 x89 xe2 x89 xa4 xe2 x80 x8910). In a single line print a single real number -- the answer to the problem. The answer will be considered correct if its absolute or relative error doesn't exceed 10 xe2 x80 x89- xe2 x80 x896. Figure to the second sample"...