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

Ex Input:
xeKSiBafhOWBbYwlGaQ, GUfIsKgafhOWBbYiFWnptAt

Ex Output:
afhOWBbY


Ex Input:
jJSSBmflUyrEMLjSycA, YkmujkSSBmflUyrKKJZ

Ex Output:
SSBmflUyr


Ex Input:
esgsJs, SKgshz

Ex Output:

gs