instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
cKsJcqYvZO, UrsJcqBC
answer:
sJcq


question:
VGRjWGHRcBdFmkVg, eSwqALQXWGHRcBdFsDXCM
answer:
WGHRcBdF


question:
AHbRpbchRaDjDykNsfcdUsZQ, lKKDjDykNsfcdMY
answer:

DjDykNsfcd