instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
JqdTDnZqSuSVcMsx, TEtDDnZqSuZa
answer:
DnZqSu


question:
zgJGhxLU, EwJGhedW
answer:
JGh


question:
JpKtFw, zwKtEQ
answer:

Kt