Skyscrapers Ltd. (480)

Fill the whole grid with numbers 1 to N acording to Skyscrapers rules. Additionally, exactly n of the buildings (marked by circles) are owned by the Skyscrapers Ltd. corporation. No two Skyscrapers Ltd. buildings are in the same row, the same column, or have the same height. Number outside the grid in a circle means that an Skyscrapers Ltd. building must be visible from that direction. A number outside the grid without a circle means that an Skyscrapers Ltd. building must not be visible from that direction. It is not needed to circle the Skyscrapers Ltd. buildings in order to be awarded the points for the puzzle.

Reference: WPC 2016 (65)