0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
20 is even, 19 is odd, 18 is even, 17 is odd, 16 is even, 15 is odd, 14 is even, 13 is odd, 12 is even, 11 is odd, 10 is even, 9 is odd, 8 is even, 7 is odd, 6 is even, 5 is odd, 4 is even, 3 is odd, 2 is even, 1 is odd,