instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
lQwpMQRxuVbJDv, UkzwpMQRxuDVT
answer:
wpMQRxu


question:
GFhJafTV, waHhJaji
answer:
hJa


question:
UCbReSfuLcbzmBCl, snQRReSfuLcbzmjqVPSdpp
answer:

ReSfuLcbzm