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

Ex Input:
jsXHot, gtXHmB

Ex Output:
XH


Ex Input:
uZSRkFDHsGXNMaggxUn, lTrQKKpsGXNMaggEdSrEX

Ex Output:
sGXNMagg


Ex Input:
FjohtyBUApMcKlZpoj, yQBBUApMcKgMXUt

Ex Output:

BUApMcK


