instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
SeXNqRAbKdLuWXgb, npsIWRAbKdLuUWSbvuS
answer:
RAbKdLu


question:
KJswoapnXz, EQswoaFyH
answer:
swoa


question:
WCAenFgpKK, oaFnFgprt
answer:

nFgp