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

Q: VXSNlHzkB, EoNlHCiL

A: NlH
****
Q: wYhGWdRC, cFGWdHEy

A: GWd
****
Q: YKQPyNQNLNdwSN, uUHgVyNQNLNdwLTx

A:
yNQNLNdw
****