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

Ex Input:
MvALRGKkpALcKdhTtnm, neMkRGKkpALcKdcaxnXEPxW

Ex Output:
RGKkpALcKd


Ex Input:
lQwpMQRxuVbJDv, UkzwpMQRxuDVT

Ex Output:
wpMQRxu


Ex Input:
dakTwyRfngRl, tOMzTyRfngush

Ex Output:

yRfng