In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

Ex Input:
jsXHot, gtXHmB

Ex Output:
XH


Ex Input:
YlhtTQgHiffTbIbBrcHMqFKCdWz, HyregFgMffTbIbBrcHYUnnQvGlx

Ex Output:
ffTbIbBrcH


Ex Input:
nzYxtwRIuBSbZhTKzBDW, FqsRIuBSbZhTKVjglI

Ex Output:

RIuBSbZhTK