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

[Q]: QECPAHsg, bUfPAHOWb
[A]: PAH


[Q]: umXfmRnUgALpFAqBaKfNfo, aOAXWnUgALpFAqBmNpTCdj
[A]: nUgALpFAqB


[Q]: BPOxJWWaIJTCpUpQtJPA, DYqyZihaIJTCpUpGTm
[A]:
aIJTCpUp