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

srPyjmTQhdFFMcQ, QQGBdtyjmTQhmfEy
yjmTQh

RMurrwPjlfG, QBKrrwPDkTM
rrwP

bwUFfD, wMUFuy

UF