instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
BmwpAnWJ, klVwpAFw
answer:
wpA


question:
UIjAMFDuxDDGkfQa, VdsHuxDDGkfZHZZ
answer:
uxDDGkf


question:
zvbXRtuZHbsUznp, wwBVbXRtuZHSBEbPgR
answer:

bXRtuZH