Rules: Fill the grid with digits 1 to n, so that each digit appears exactly once in every row, column. Each digit represents a building with the height of that digit itself. High buildings block the view, preventing to see lower buildings. Clues outside the grid represent the two possibilities for the number of the buildings that can be seen from the corresponding directions.
Background: Today (03.09.12) I was searching a skyscrapers variation to prepare for upcoming 24 HPC in Roland Skyscrapers web page. At the bottom of the page, Roland asks for new variations. After that the idea came up, and I think it turned out well.