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

[Q]: feYKRk, PrYKMW
[A]: YK


[Q]: oGaGjsaKsUpLQAg, iDGjsaKsUoYGuta
[A]: GjsaKsU


[Q]: tjimBdhRDosbMRBESMjf, hiRfHZbTmBdhRDosbNuWmCaCEY
[A]:
mBdhRDosb