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

Q: ARGchkRez, kUwchkZPE

A: chk
****
Q: gTjTwC, OUjTgM

A: jT
****
Q: nOzKCZhe, aBzKCZAfV

A:
zKCZ
****