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

[EX Q]: RinootTGLjbRGYznmBdH, oRMtTGLjbRGYzwEVHsjW
[EX A]: tTGLjbRGYz

[EX Q]: NwmTIZSnlKGG, qAYIZSnfWRd
[EX A]: IZSn

[EX Q]: gIerubuzbGkuD, PdherubuzKGKO
[EX A]:
erubuz