instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
iaXeqfIrYKxPJRXxfSm, rIYKxPJRXxfsjVsqe
answer:
YKxPJRXxf


question:
trHTzJpm, aCHTzVVA
answer:
HTz


question:
tMnCsVyFAzXwQJ, rgsVyFABd
answer:

sVyFA