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