Let be a positive integer. Find the maximum number of diagonals in a regular -gon one can select, so that any two of them do not intersect in the interior or they are perpendicular to each other.
Let $n \geq 3$ be a positive integer. Find the maximum number of diagonals in a regular $n$-gon one can select, so that any two of them do not intersect in the interior or they are perpendicular to each other.
Školjka 
be a positive integer. Find the maximum number of diagonals in a regular 
-gon one can select, so that any two of them do not intersect in the interior or they are perpendicular to each other.