instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
UldKHMpUYADGfEUGcSon, nPHMpUYADGfEKqHCLPmL
answer:
HMpUYADGfE


question:
yRhCObvPZYoKUoQnyaatR, NHzLJYPZYoKUoQnJnIsZxC
answer:
PZYoKUoQn


question:
crDcWAkzfaK, kwjyjcWAkzfphUMt
answer:

cWAkzf