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

[EX Q]: hRVyvwHqnN, geHeyvwHqiBiYJ
[EX A]: yvwHq

[EX Q]: HEVqGddewrNqiZ, iyvlddewrNXr
[EX A]: ddewrN

[EX Q]: bGSoSkgiANq, PSSoSkgiAOYVYwTU
[EX A]:
SoSkgiA