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

Example Input: oZZUNCUHtIiauDxQ, OdindZUNCUHtIiLQmWJJf
Example Output: ZUNCUHtIi

Example Input: oZNKLmfxecDfkXEGFkRBYk, tReqkiExecDfkXEGtNZpJVRxC
Example Output: xecDfkXEG

Example Input: lEQfuMUDnaeeGhNyGkhMNXqOan, GctJFuFoUDnaeeGhNyKSFv
Example Output:
UDnaeeGhNy