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

Q: QgkpBHsrfRYJCa, AdjbKLpBHsrfbpBC

A: pBHsrf
****
Q: HXYkGv, GCYksu

A: Yk
****
Q: UeyroMmcSwIy, jSoMmcSoldJ

A:
oMmcS
****