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

Q: PzXzvmYrlGZgOBk, iKnzvmYrlGZgOrs

A: zvmYrlGZgO
****
Q: mvIvSzMtYsfVLdaGEmef, wnzMtYsfVLdaKm

A: zMtYsfVLda
****
Q: QTBHOu, LrBHNx

A:
BH
****