instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
IKrQfT, crrQRg
answer:
rQ


question:
XjYkMfARxWBSBjuXyDrFt, EtUxIfiHkMfARxWBSckTLTTnR
answer:
kMfARxWBS


question:
LaTHFpWmRN, uzZvHHFpWmcwnzv
answer:

HFpWm