x[Ascending]
|------------------------------5-7-8-|
|------------------------5-6-8-------|
|------------------4-5-7-------------|
|--------------5-7-------------------|
|--------5-7-8-----------------------|
|-5-7-8------------------------------|
[Descending]
|-8-7-5-----------------------------|
|-------8-6-5-----------------------|
|-------------7-5-4-----------------|
|-------------------7-5-------------|
|-----------------------8-7-5-------|
|-----------------------------8-7-5-| 