Adding 1, Subtracting 1

Front 1

1
+ 1

Back 1

2

Front 2

1
+ 2

Back 2

3

Front 3

1
+ 3

Back 3

4

Front 4

1
+ 4

Back 4

5

Front 5

1
+ 5

Back 5

6

Front 6

1
+ 6

Back 6

7

Front 7

1
+ 8

Back 7

9

Front 8

1
+ 9

Back 8

10

Front 9

10
- 1

Back 9

9

Front 10

9
- 1

Back 10

8

Front 11

8
- 1

Back 11

7

Front 12

7
- 1

Back 12

6

Front 13

6
- 1

Back 13

5

Front 14

5
- 1

Back 14

4

Front 15

4
- 1

Back 15

3

Front 16

3
- 1

Back 16

2

Front 17

2
- 1

Back 17

1

Front 18

1
- 1

Back 18

0