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

Example Input: esIMEOgV, tNIMEybb
Example Output: IME

Example Input: XEvxzelZaWRO, zXIelZaWBUn
Example Output: elZaW

Example Input: ZORRUO, meRRNp
Example Output:
RR