instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
wXGerDNhSNnCCedyzskswVnh, BfFNhSNnCCedybrUbI
answer:
NhSNnCCedy


question:
SFQHJlK, dHfQHJoUC
answer:
QHJ


question:
MLMQtdMWAFcfHiyNDBSrXZC, KiZcTWAFcfHiynKX
answer:

WAFcfHiy