instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
OhMVLbQhBxEaOZY, iDVLbQhBxBiiD
answer:
VLbQhBx


question:
ZyrpGdXvvtrKQIxU, CLNGdXvvtrKQDpicfqLdt
answer:
GdXvvtrKQ


question:
RAiRNlOSbit, TXvqRNlOSSqxgN
answer:

RNlOS