instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
WFAPUCgVYbmZiFlacUzyv, xQFiekrgPUCgVYbmZUEtl
answer:
PUCgVYbmZ


question:
DUhUbmfLuOFAQann, kwnzfLuOFAErR
answer:
fLuOFA


question:
FjcIzymE, FzIzyXa
answer:

Izy