7            +-----+  
6            |     |  
5   /\       |     |  
4  +-+       |     |  
3  | | +-+   | ____|__    +---+  
2 \| | | |   |/       \   |   |  
1  \ | | |   /         \  |   |  
0   +-------+           +-+---+  
0123456789012345678901234567890

The numberline at the bottom is optional but may help
you test your program.