规则Rules：
填入1~3，使得每行、列、宫内都是两组1~3不重复。外提示是这一方向上的摩天楼数。
Write1~3, make each Row/Column/Box contain 2 groups 1~3. The outside clue is the skyscraper number on this direction.
◆摩天楼数 Skyscraper number
摩天楼数表示从这一方向上观察，大数字能遮住小数字时，可以看见的数字的个数。
The skyscraper number shows how many numbers can be seen in this direction, when larger number will hide lower ones.
