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

Ex Input:
gWMyioGBRpwcXfr, AOQGBRpwcSccqBE

Ex Output:
GBRpwc


Ex Input:
feYKRk, PrYKMW

Ex Output:
YK


Ex Input:
dqVrgv, rhVrUX

Ex Output:

Vr