instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
jLbHvZmecfxMcGLXGVsO, erFBGmecfxMcJtDyKGZ
answer:
mecfxMc


question:
SIIPePlrkftKkzfgdjg, JqNnXHrkftKkzOMUwmc
answer:
rkftKkz


question:
QXfOTSxbCSISiHz, IDNItSxbCSIue
answer:

SxbCSI