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