1/20-2/20-3/20 1 4/20 2 3 1 2 4 5 1 2 3 4 6 1 5/20 2 3 7 8 1 2 9 1 6/20 2 3 10 1 2 11 1 2 3 12 1 7/20 2 13 1 2 3 14 1 2 3 4 8/20 5 15 1 2 16 1 2 17 1 2 3 18 9/20 1 2 3 4 19 1 2 20 1 2 3 4 5 10/20 21