15 20 
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0 1 1
0 2 1
0 3 1
0 4 1
1 5 1
2 6 1
2 7 1
3 7 1 
3 8 1
4 9 1
5 10 1
6 10 1
6 11 1
8 11 1
8 12 1
9 12 1 
10 14 1
11 13 1
12 14 1
13 14 1