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

[EX Q]: qMnjlfIsQRtUlPggCpHqu, gfVndMwYDIsQRtUlPgqBJKCX
[EX A]: IsQRtUlPg

[EX Q]: IobjElBjKvpepE, kRulBjKvvxU
[EX A]: lBjKv

[EX Q]: WMiZFjCvPgn, gqVFjCvPky
[EX A]:
FjCvP

