instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
HHJAHyvNCGmJEljWrjvHOqf, msPVEbNCGmJEljsKRX
answer:
NCGmJElj


question:
NNpkdhvgT, BMkAkdhvrwV
answer:
kdhv


question:
dNnubiTR, nkRubiNnj
answer:

ubi