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

Q: pJqqIW, Ivqqxw

A: qq
****
Q: GBTHKtWUzK, ovVNKtWUmVJF

A: KtWU
****
Q: lUYqIXBDC, EWOqIXbGE

A:
qIX
****