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

Example Input: UiaECWZf, gRyaECWLGRl
Example Output: aECW

Example Input: TnHJcxtwcZ, XFdHJcxNKw
Example Output: HJcx

Example Input: WCinZl, vQinag
Example Output:
in