1 2 3 4
E E E E
* X - t
  * X u
    * t
      *
handedness 1 2 3 R
handedness 1 2 4 R
handedness 2 3 4 L
sheetS 1 4 3
sheetD 2 1
length 1 E 5 100
length 2 E 5 100
length 3 E 5 100
length 4 E 5 100