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

Ex Input:
pJqqIW, Ivqqxw

Ex Output:
qq


Ex Input:
BUvWkxrAvDQG, rHrkxrAkCE

Ex Output:
kxrA


Ex Input:
PXRkNcKsVZQjQLQrO, gNutrtNcKsVZQGaR

Ex Output:

NcKsVZQ