0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
0
X
X
X
X
1
2
X
X
3
X
X
X
4
X
5
X
X
6
X
X
X
7
X
X
8
X
9
X
X
10
X
X
X
X
11
12
X
X
13
X
14
X
X
X
15