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

[Q]: bOvlVNWf, iivlVzWt
[A]: vlV


[Q]: QRPOwtZATjDoJDdRNNSOH, wiafFMwpAjDoJDdRNNuCDZ
[A]: jDoJDdRNN


[Q]: kkwdyKEHUdLnxBok, URKEHUdLnQl
[A]:
KEHUdLn