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:
rduIwWNGM, AJqYIwWNaCap
answer:
IwWN


question:
aERdTc, WvRdnG
answer:

Rd