In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

Q: dxqZUOvRprXyFfjQfTWBhR, biSVjOvRprXyFfDtuFWQ

A: OvRprXyFf
****
Q: UZbmGVDzIaf, qfHwqGVDzIsd

A: GVDzI
****
Q: DPdLWr, WJdLTH

A:
dL
****