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:
TWVTGNBh, nEVTGWq
answer:
VTG


question:
oqgwir, qUgwmM
answer:

gw