instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
CMrTXnTnTVaR, srnXnTnTDNULO
answer:
XnTnT


question:
srPyjmTQhdFFMcQ, QQGBdtyjmTQhmfEy
answer:
yjmTQh


question:
vaRVWALFBtlqDnDWKgJfmwMip, iVlqDnDWKgJfpmCphdK
answer:

lqDnDWKgJf