instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
euQWhCovKplukMYznXcD, XAfMhKdzhCovKplukMcMlSuBw
answer:
hCovKplukM


question:
HSsyZzZLZAAq, MFEZzZLJC
answer:
ZzZL


question:
GuGJGRanuoNUBKdTrBT, qiMKGRanuoNUBKuH
answer:

GRanuoNUBK