1x 
1x  |
 |
4x 
-- 2x  |
 |
2x 
== 2x  |
 |
2x 
2x |
 |
2x
2x  |
 |
2x  |
 |
1x 
2x  |
 |
| 1x
1x |
 |
2x  |
 |
1x 
-- 1x  |
 |
1x 
== 1x  |
 |
1x 
1x |
 |
2x 
1x 
== 1x  |
 |
1x 
1x |
 |
1x 
1x |
 |
1x 
1x 
1x |
 |
2x 
1x  |
 |
1x 
2x  |
 |
| 1x
1x |
 |
2x 
2x 
2x |
 |
2x 
1x |
 |
1x |
 |
| + |
 |
 |
|
