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

[EX Q]: DUhUbmfLuOFAQann, kwnzfLuOFAErR
[EX A]: fLuOFA

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

[EX Q]: gqYuiIvxVueWxFZjlkPgEs, KsAgEwjAtiIvxVueWxFxtvLSE
[EX A]:
iIvxVueWxF