instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
oDdulHNcCdgbRGxiBTxM, kDcCdgbRGnsJlvas
answer:
cCdgbRG


question:
sbQJFbUtmnKaEJePFPeRM, QzfvkdZbUtmnKaEJNrWD
answer:
bUtmnKaEJ


question:
fRdmMumy, XKmmMuQv
answer:

mMu