SE-SKOLORNAS 2004 Problem 5

A square of side $n \ge 2$ is divided into $n^2$ unit squares ( $n \in N$ ). One draws $n-1$ lines so that the interior of each of the unit squares is cut by at least one of these lines. (a) Give an example of such a configuration for some $n$ . (b) Show that some two of the lines must meet inside the square.