2.1.3 Maple

A grade: { 1, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 50, 52 }

B grade: { 2, 4, 16, 17, 18, 19, 22, 23, 24, 25, 28, 29, 30, 31, 32, 33, 34, 35, 38, 39, 40, 43, 44, 45, 48, 49 }

C grade: { 51, 53 }

F grade: { 20, 21, 26, 27, 36, 37, 41, 42, 46, 47 }