instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
hGyDyQYdxCCuD, BQiFOyQYdxel
answer:
yQYdx


question:
osmJJcZlDAXBgJFsJKa, rzPNlDAXBgJYrgXlH
answer:
lDAXBgJ


question:
Aofafw, gmfaEy
answer:

fa