A grade: { 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 18, 19, 20, 22, 23, 24, 25, 26, 28, 29, 31, 32, 34, 36, 38, 48, 49, 50, 51, 52, 53 }
B grade: { 10, 17, 27, 30, 33, 35, 39 }
C grade: { 21, 37, 40, 41, 42, 43, 44, 45, 46, 47 }
F grade: { }