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

Q: mjCEUoPmeKbvCgUtUL, SrHtrPmeKbvYpQAVp

A: PmeKbv
****
Q: nXVXIEGP, fkXIEkU

A: XIE
****
Q: nNhgRJ, HGhguZ

A:
hg
****