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

Q: SFQHJlK, dHfQHJoUC

A: QHJ
****
Q: gwVLygvd, VOQLyglfo

A: Lyg
****
Q: mWXTLreV, XMpXTLPRY

A:
XTL
****