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

Q: sbQJFbUtmnKaEJePFPeRM, QzfvkdZbUtmnKaEJNrWD

A: bUtmnKaEJ
****
Q: RMurrwPjlfG, QBKrrwPDkTM

A: rrwP
****
Q: erPPXPCnBJqK, IbuPCnBJSIrOA

A:
PCnBJ
****