instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
ugDpSMRvHM, DDwSMRvxw
answer:
SMRv


question:
zbSNNVc, agSNNtOQ
answer:
SNN


question:
wcJmSloqlddFOfv, szhUIAqzSloqlddFDJz
answer:

SloqlddF