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

Example Input: MSzHyOuaJILkeY, eUibEHoHyOuaJIhfvXy
Example Output: HyOuaJI

Example Input: DhhYhrqVMXSoyvXQwqPKzWARAP, CaMXSoyvXQwqcDDtMsVqD
Example Output: MXSoyvXQwq

Example Input: etCBJvveAZf, maiEsCBJvveKlf
Example Output:
CBJvve