xxxxxxx  xxxxxx  xxxxxx  xxxxxxx
x                              x
x                              x
x     s                        x
x                              x
x                              x
xxxxxxxxxxxxxxx  xxxxxxxxxxxxxxx
                           s    
                                
x                              x
x        e                     x
xxxxxxx  xxxxxxxxxxxxxx  xxxxxxx
xxxxxxx  xxxxxxxxxxxxxx  xxxxxxx
x             x                x
x             x                x
              x                 
              x                 
x             x                x
x             x         e      x
x                              x
x                              x
x             x                x
x             x                x
              x                 
              x                 
x             x                x
x             x                x
x             x                x
x     s       x        s       x
x             x                x
x             x                x
xxxxxxx  xxxxxx  xxxxxx  xxxxxxx