instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
CCzKRbuEAmN, qTLzKRbuhEqq
answer:
zKRbu


question:
jJjsASFfCqVV, AkjsASFfBFwPy
answer:
jsASFf


question:
gxvzSeOjjlaDz, qwvzSeOjjup
answer:

vzSeOjj