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

[EX Q]: TvNVpHLPYjBCeUpyxlzFZ, tgKdPKVYjBCeUpyPK
[EX A]: YjBCeUpy

[EX Q]: yQRDycTycwH, ImycTycrR
[EX A]: ycTyc

[EX Q]: ljwjMioOwfOltGBaE, TneNGsoOwfOlxnWWW
[EX A]:
oOwfOl