instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
EyvnjbVLF, vqnjblzR
answer:
njb


question:
mRVieYomZqJXaTDsShCyfPW, ifOAlnptmZqJXaTDsVMqY
answer:
mZqJXaTDs


question:
ySZEbs, VkZEYs
answer:

ZE