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