+---+
| 1 |
+---+
|
|
v
+---+---+----+
| A | B | C |
+---+---+----+
+---+
| 2 |
+---+
|
|
v
+---+---+----+
| A | B | C |
+---+---+----+
+---+
| 1 |
+---+
|
|
v
+---+---+----+
| A | B | C |
+---+---+----+
+---+
| 2 |
+---+
|
|
v
+---+---+----+
| A | B | C |
+---+---+----+