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

[EX Q]: UiaECWZf, gRyaECWLGRl
[EX A]: aECW

[EX Q]: yITbYie, TlqTbYomH
[EX A]: TbY

[EX Q]: xxocGoSwCM, OPYEocGoDca
[EX A]:
ocGo