instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
RwduMBkDazrwZP, UPzcwtWMBkDazrAw
answer:
MBkDazr


question:
WTnsmP, INnsIM
answer:
ns


question:
paFCGMizAQWlRiPHSeYKkByz, FzuOAQWlRiPHSWUGkyBd
answer:

AQWlRiPHS