instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
JAGuNgaUudP, eojvKNgaUuQg
answer:
NgaUu


question:
MSxTzCpiJAplpzSvLlNJS, oScCpiJAplpNVrqkn
answer:
CpiJAplp


question:
QozfdYyN, pGFzfdWfA
answer:

zfd