6-1
=5
7-1
=6
8-1
=7
13-1
=12
18+1
=19
14-1
=13
5-1
=4
2-1
=1
9-1
=8
14 + 1
=15
12+1
=13
11+1
=12
18-1
=17
13+1
=14
5+1
=6
19-1
=18
1+1
=2
3-1
=2
16+1
=17
19+1
=20
2+1
=3
15-1
=14
4+1
=5
3+1
=4
4-1
=3
11-1
=10
12-1
=11
10-1
=9
10+1
=11
6+1
=7
17-1
=16
15+1
=16
7+1
=8
1-1
=0
8+1
=9
17+1
=18
16-1
=15
9+1
=10
20-1
=19