instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
OrcQOvMBhmwP, mnWrzcQOvMBnLwI
answer:
cQOvMB


question:
BmwpAnWJ, klVwpAFw
answer:
wpA


question:
UNDwiaPMgUutgjC, iLxEaPMgUuKpK
answer:

aPMgUu