Skyscrapers 2 in 1 (457)

Insert number from 1 to N where N is the size of the grid into each cell so that no digit repeats in any row or column. Each number in the grid represents the height of a building. The clues outside of the grid indicate how many buildings can be seen when looking from the corresponding direction. Higher buildings block the view of smaller buildings. The clues in the top grid give the sum of numbers from both grids at the corresponding position.

Reference: WPC 2016 (65)