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

Q: kUoqCMPFTqGE, guoqCMPkwJs

A: oqCMP
****
Q: QgkpBHsrfRYJCa, AdjbKLpBHsrfbpBC

A: pBHsrf
****
Q: McJNpWkCm, UHoNpWkkb

A:
NpWk
****