instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
nhGinCtvLartcMPhJwGRbpZNrq, iQJlFKayEartcMPhJwDRROB
answer:
artcMPhJw


question:
wDSKHtWbCDqTeoBeiYHdcZD, MydQCwqTeoBeiYHdYMp
answer:
qTeoBeiYHd


question:
GOfGdVavkaRpPzGhxq, ffdXVgMYdVavkaRpOURSgmd
answer:

dVavkaRp