After a drawn-out mooclear arms race, Farmer John and the Mischievous Mess Makers have finally agreed to establish peace. They plan to divide the territory of Bovinia with a line passing through at least two of the n outposts scattered throughout the land. These outposts, remnants of the conflict, are located at the points ( x 1 , y 1 ), ( x 2 , y 2 ), ..., ( x n , y n ) . In order to find the optimal dividing line, Farmer John and Elsie have plotted a map of Bovinia on the coordinate plane. Farmer John's farm and the Mischievous Mess Makers' base are located at the points P = ( a , 0) and Q = ( - a , 0) , respectively. Because they seek a lasting peace, Farmer John and Elsie would like to minimize the maximum difference between the distances from any point on the line to P and Q . Formally, define the difference of a line relative to two points P and Q as the smallest real number d so that for all points X on line , | PX - QX | ≤ d . (It is guaranteed that d exists and is unique.) They wish to find the line passing through two distinct outposts ( x i , y i ) and ( x j , y j ) such that the difference of relative to P and Q is minimized. The first line of the input contains two integers n and a ( 2 ≤ n ≤ 100 000 , 1 ≤ a ≤ 10 000 ) — the number of outposts and the coordinates of the farm and the base, respectively. The following n lines describe the locations of the outposts as pairs of integers ( x i , y i ) ( | x i |, | y i | ≤ 10 000 ). These points are distinct from each other as well as from P and Q . Print a single real number—the difference of the optimal dividing line. Your answer will be considered correct if its absolute or relative error does not exceed 10 - 6 . Namely: let's assume that your answer is a , and the answer of the jury is b . The checker program will consider your answer correct, if . In the first sample case, the only possible line is y = x - 1 . It can be shown that the point X which maximizes | PX - QX | is (13, 12) , with , whic