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

Example Input: IVnbnqBqdPcXfHotUzCYoaGQy, PAlyypBRRBqdPcXfHotpZs
Example Output: BqdPcXfHot

Example Input: PShMbsbexXGlpBuMMDZZS, sVqGxSexXGlpBxuHXoI
Example Output: exXGlpB

Example Input: aeQjEeiWGONmzGimhGiw, RIEeiWGONmOZuVYr
Example Output:
EeiWGONm