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