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

[EX Q]: NxgzLSzFGa, JvLzLSzsuj
[EX A]: zLSz

[EX Q]: jAinxmaQUrmu, jqeEnxmaQUrWlrEqW
[EX A]: nxmaQUr

[EX Q]: ByGQgViMNOX, bXuBgViMGsJT
[EX A]:
gViM