instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
KvPFobZEGs, eKFobZEtnm
answer:
FobZE


question:
SeXNqRAbKdLuWXgb, npsIWRAbKdLuUWSbvuS
answer:
RAbKdLu


question:
xBXEfEpWjuutUAoTFUo, yAtAZIUjYjuutUAoTFtmALilgJ
answer:

juutUAoTF