e----0----0----1----1---
b----1----0----1----1---
e----0----0----0----1---
b----1----0----1----1---
e----0----3----0----3----1----
b----1----3----1----3----1----
e----0----0----1----1---
b----1----1----1----1---
e----0----0----1----1---
b----1----0----1----1---
e----0----0----0----1---
b----1----0----1----1---
e----0----3----0----3----1----
b----1----3----1----3----1----
e----0----0----1----1---
b----1----1----1----1---