instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
ylyLVUjsmMrXMFAPDGIZsHq, cYymMrXMFAPjm
answer:
mMrXMFAP


question:
FSwxBJ, iTwxAa
answer:
wx


question:
ebzknKFqKCUQbjgjIVhgXoUiz, zYNDynBcKCUQbjgjIwSLvg
answer:

KCUQbjgjI