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

Example Input: elloYaejTczBiiNOU, XoCPzloYaejTcXYtKODL
Example Output: loYaejTc

Example Input: lkFGXvTkKm, wwELXvTkcOnG
Example Output: XvTk

Example Input: UgEGYBgZwhLOJ, jYkOJUEGYBgZHgif
Example Output:
EGYBgZ