10
0 a 1
0 b 0
1 a 4
1 b 3
2 a 3
2 b 2
3 a 1
3 b 8
4 a 1
4 b 9
5 a 6
5 b 0
6 a 0
6 b 1
7 a 3
7 b 3
8 a 8
8 b 9
9 a 0
9 b 8
3 8
10
0
1
2
3
4
5
6
7
8
9