Disc Golf

The cows are out on a fine day to play disc golf. Bovines are
extremely skilled at disc golf, and can make their discs follow any
path they wish (they can curve around obstacles if necessary).

A particular path is surrounded on both sides by dense forest with
N (0 <= N <= 1000) trees of particular radii down the path.  Tree
i is located at (x_i,y_i) and has radius r_i (all integers in this
problem fit handily into 32 bits).  The forest lies below the line
y=0 and above the line y=H (1 <= H <= 1,000,000):

The cows must not throw the disc into the forest or into a tree,
and they prefer to play with large discs, because they are more
stable and the cows can throw them more easily. Help the cows to
find the largest disc that they can throw from one end of this path
to the other. They know that some solution is always possible.



                 forest
       ------------------------
           O            O 
START                            END   
              O             O
           O         O
       ------------------------
                 forest



PROBLEM NAME: discgf


INPUT FORMAT:

* Line 1: Two integers: N and H.

* Lines 2..N+1: Line i+1 contains three integers: x_i, y_i, and r_i


SAMPLE INPUT:

1 10
3 4 2


OUTPUT FORMAT:

* Line 1: A decimal answer rounded to two decimal places,
        representing the radius of the largest possible disc.


SAMPLE OUTPUT:

2.00