instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
tyVlHfTPLRSdFilXnSfqQ, bkTPLRSdFiMgXC
answer:
TPLRSdFi


question:
rqhQxQQDdYwemFiiwcfVx, cEQDdYwemFtwpfNJC
answer:
QDdYwemF


question:
marmNnzWVKqCe, jkddnQRNnzWVKqNztqp
answer:

NnzWVKq