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

Example Input: ahPbomjSH, rBbomynK
Example Output: bom

Example Input: xeKSiBafhOWBbYwlGaQ, GUfIsKgafhOWBbYiFWnptAt
Example Output: afhOWBbY

Example Input: OuahKKuxFsUIEyMii, ZjRQtcuxFsUIEwpKwS
Example Output:
uxFsUIE