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:
pJqqIW, Ivqqxw
answer:
qq


question:
UQMwkxwtlVLLnvStDJfZdSA, RFubpRSvvtlVLLnvStDdu
answer:

tlVLLnvStD