instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
PIcbiJj, hedcbiZHF
answer:
cbi


question:
STvKOHq, XMGvKOdyM
answer:
vKO


question:
suFEYERkrEczuosCbLVCLrO, akwjRRkrEczuosCuXCw
answer:

RkrEczuosC