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

Ex Input:
ohueEOjHvAuoFVmMFft, ovdJPqOjHvAuoFVGbvxzlnE

Ex Output:
OjHvAuoFV

Ex Input:
DGvUCrUVlUnQBShkWnfnceGasvI, NfzGUnQBShkWnpLMnY

Ex Output:
UnQBShkWn

Ex Input:
PIiDXhJhbnJy, uXUCKciDXhJhSAQ

Ex Output:
iDXhJh