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

Q: LudFxiaqbX, UWMPnFxiaqikiDx

A: Fxiaq
****
Q: rqhQxQQDdYwemFiiwcfVx, cEQDdYwemFtwpfNJC

A: QDdYwemF
****
Q: gTPUchng, ePSUchtb

A:
Uch
****