instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
HhBhJMpxpty, MxTJMpxnQEf
answer:
JMpx


question:
OVZxWYzAAxG, rStOxWYzJeoC
answer:
xWYz


question:
GuHLAZGGzdMtIrIluq, lWmHLAZGGzdMuMM
answer:

HLAZGGzdM