instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
OYERnjubLFovtcS, FngzQJVGERnjubLFafmzq
answer:
ERnjubLF


question:
iMwanJBuMdiZDL, kIafHeBuMdiZmKNA
answer:
BuMdiZ


question:
tOdQBKaxPN, CFKeQBKaQmeF
answer:

QBKa