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

Input: Consider Input: ilgSzrcUKLTNLJbMKMKSt, hFXIuUKLTNLJbMKWxSCkDjY

Output: UKLTNLJbMK

Input: Consider Input: xeKSiBafhOWBbYwlGaQ, GUfIsKgafhOWBbYiFWnptAt

Output: afhOWBbY

Input: Consider Input: xaikeXDlAo, AyANikeXDGS
Output: ikeXD