1
2
x2
S1
S1
x2
x1
S1
4
x2
x1
x2
x2
S1
3
S2
4
S2
x1
x2
x2
S2
S1
x2
x2
x2
S1
S2
6
5
4
5
x1
x2
x2
x2
S2
x2
x2
S2
x2
S2
S2
5
7
5
9
6
7
x1
x1
x2
S2
x2
x2
S2
8
x2
S2
S2
S2
S2
8
S2
x1
10
x1
x1
x2
x1
x1
S2
x1
S2
S1
S2
S1
6
x1
x1
S2
11
9
12
10
x2
S2
x2
x1
S1
S2
x2
x2
S1
S2
S2
7
13
14
x1
x1
S1
x2
x2
S1
x2
x2
S3
x2
S3
S3
S3
8
16
15
x1
x2
x1
x2
S3
S1
x2
x4
x4
S3
S1
S3
S3
9
18
17
x1
x1
x1
x1
S1
x3
x1
x3
S1
x2
x2
S1
S1
19
x1
S1
x2
x2
S1
10
20
17
S1
21
19
x1
x1
x1
x1
S1
B3
x1
x1
x2
A238
11
22
x1
x1
x1
x1
x1
A238
A338
12