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

[EX Q]: libDFDxIgRiglWfxMVRr, yMltDxIgRiglpms
[EX A]: DxIgRigl

[EX Q]: yjoJzBGdwfOhsceoOpoap, uSLMdBGdwfOhsIQHBijd
[EX A]: BGdwfOhs

[EX Q]: kdQowEfeHF, vFowEfkC
[EX A]:
owEf