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:
ocjsZZfSBBopDtgWUT, rWmgzsZZfSBBoGWQ
answer:
sZZfSBBo


question:
uRLpAWCotLmxcSmKyvo, laotLmxcSmKyBwVfJB
answer:

otLmxcSmKy