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

Ex Input:
mXHhaCEIwqwEZcz, JZPXbYHhaCEIwZmna

Ex Output:
HhaCEIw


Ex Input:
Owbiay, exbime

Ex Output:
bi


Ex Input:
FPXtFqtEehkOHMbnjuLQg, lPzwtmtEehkOHMbnMKtWXMs

Ex Output:

tEehkOHMbn