instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
jeQzwP, kSQzxq
answer:
Qz


question:
iwSQnplQZFbXQ, lHWnplQZFzswgU
answer:
nplQZF


question:
UHTUCVkTlgZZGdyhToDLV, NumlgZZGdyhCVSX
answer:

lgZZGdyh