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

Ex Input:
lQwpMQRxuVbJDv, UkzwpMQRxuDVT

Ex Output:
wpMQRxu


Ex Input:
DwLGzwYOWjtzIunE, TTViSbkwYOWjtzNqUOOz

Ex Output:
wYOWjtz


Ex Input:
ufRKFzOjMgupbCBhSGYPkXFWeNd, lXRqupbCBhSGYPZty

Ex Output:

upbCBhSGYP