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

Q: GrvtMjEvRlmN, ifGOWMjEvRPSOZK

A: MjEvR
****
Q: PIcbiJj, hedcbiZHF

A: cbi
****
Q: DHQtJTyqZE, CvFQtJTyqJPLpDc

A:
QtJTyq
****