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

[EX Q]: jJSSBmflUyrEMLjSycA, YkmujkSSBmflUyrKKJZ
[EX A]: SSBmflUyr

[EX Q]: wYhGWdRC, cFGWdHEy
[EX A]: GWd

[EX Q]: HnfMqzTWfOpCcQdPWLVhMO, pwCzTWfOpCcQdbcgCtacVi
[EX A]:
zTWfOpCcQd