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

[EX Q]: ZyrpGdXvvtrKQIxU, CLNGdXvvtrKQDpicfqLdt
[EX A]: GdXvvtrKQ

[EX Q]: dReySjyqecU, loSjyqiRl
[EX A]: Sjyq

[EX Q]: lKdaPQ, rNdaKD
[EX A]:
da