instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
ktABEFESAVHZkkY, uMjxiESAVHZkZgWUte
answer:
ESAVHZk


question:
xzMUdHcoYJFWLOILjrg, vCscoYJFWLzO
answer:
coYJFWL


question:
JNuVNqguurJXdIjbxF, GQuSPiqguurJXqtarWn
answer:

qguurJX