instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
CxosNa, ikosdx
answer:
os


question:
cxYVucnmEQopeWHrPJ, jNnOaYVucnmEQoSE
answer:
YVucnmEQo


question:
RxAadPcgnZhiS, KMoWdPcgnZstbN
answer:

dPcgnZ