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

Example Input: yywhNdZQkLSzbOvhluicHA, lfZQkLSzbOvhVC
Example Output: ZQkLSzbOvh

Example Input: IVnbnqBqdPcXfHotUzCYoaGQy, PAlyypBRRBqdPcXfHotpZs
Example Output: BqdPcXfHot

Example Input: XTbnJpbYeUutKDtANF, yRtrGmgMXnJpbYeUutKsaBmZnX
Example Output:
nJpbYeUutK