instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
iupYjFXrrMqWzJSLUSwmEukHc, hqajjWrrMqWzJSLnF
answer:
rrMqWzJSL


question:
aBlALASwuwTZmy, MdwASwuwIW
answer:
ASwuw


question:
kFQHtANdqXnDua, AwUmtANdqkH
answer:

tANdq