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:
nXVXIEGP, fkXIEkU
answer:
XIE


question:
eeCaTwmt, WqSCaTFl
answer:

CaT