2.1.2 Mathematica

A grade: { 2, 3, 7, 16, 19, 20, 32, 33, 34 }

B grade: { 9, 10, 11, 12, 13, 14, 15, 25, 26, 27, 28, 29, 30, 31 }

C grade: { 1, 4, 5, 6, 8, 17, 18, 21, 22, 23, 24 }

F grade: { }