A grade: { 1, 3, 4, 5, 7, 8, 10, 11, 12, 14, 15, 17, 18, 19, 23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 38, 40, 41, 42, 44, 46, 53, 54, 56, 57, 58, 59, 60, 61, 64, 65, 66 }
B grade: { 2, 6, 9, 13, 16, 20, 21, 22, 30, 34, 36, 50, 51, 52, 55, 62, 63, 67, 68 }
C grade: { }