instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
nxTtNYaazlOyEBApiUSJS, BLazlOyEBCV
answer:
azlOyEB


question:
BpGFyhLez, DfFyhuJY
answer:
Fyh


question:
ukwAuQ, KMwAOe
answer:

wA