instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
sRpnJlgECTHh, JXfmNJlgECKyry
answer:
JlgEC


question:
LudFxiaqbX, UWMPnFxiaqikiDx
answer:
Fxiaq


question:
nLFauTEmOKzxwEoKj, wgmbEmOKzxrNJu
answer:

EmOKzx