instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
XYnCjAWPHHJ, gmCjAWPHpmwVsm
answer:
CjAWPH


question:
MriFNpGM, yaiFNduk
answer:
iFN


question:
mZVkoTmkwQkd, QdooTmkHi
answer:

oTmk