1|-3---------3----------3------3----------3----------3-------- 
2|----3---------3-----------3------3---------3----------3----- 
3|-------4---------4-------------------4---------4------------- 

1|-0---------0--------0----------- 
2|----1---------1-------------4-------- 
3|-------0---------0------0------------ 

ของง่ายๆ