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

Q: QEEVsnbQIgrxaZmflaZ, dPSbljkdQIgrxaZmgVzMT

A: QIgrxaZm
****
Q: VRamNL, mUamIB

A: am
****
Q: zdCdtyxXhm, qACdtyxXtf

A:
CdtyxX
****