Irregular Skyscrapers (497)

Place a number from 1 to N into each cell so that each digit appears exactly once within a row or a column. Each number in the grid represents the height of a skyscraper. The clues outside of the grid indicate how many skyscrapers can be seen when looking from the corresponding direction. Higher skyscrapers block the view of smaller ones. N will be given in a circle next to the puzzle.

Reference: WPC 2016 (65)