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

Example Input: YKpdeJQhzyYiPoODACUu, mjmnIlCehzyYiPoOzZ
Example Output: hzyYiPoO

Example Input: OFbCjZDoRRlLsMU, DcCjZDoRRtld
Example Output: CjZDoRR

Example Input: UlernEufdYrIntlAPZdk, IrbnufdYrIntaQ
Example Output:
ufdYrInt