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

[EX Q]: zqRbqwgmqGIAGTeeoGFOSr, RFnLqwgmqGIAGLcEvAWxY
[EX A]: qwgmqGIAG

[EX Q]: jsXHot, gtXHmB
[EX A]: XH

[EX Q]: UHTUCVkTlgZZGdyhToDLV, NumlgZZGdyhCVSX
[EX A]:
lgZZGdyh