2.1.7 Giac

A grade: { 4, 9, 14, 15, 19, 23, 27, 28, 31, 34 }

B grade: { }

C grade: { 1, 2, 3, 6, 7, 8, 11, 12, 13, 16, 17, 18, 20, 21, 22, 24, 25, 26, 29, 30, 32, 33 }

F grade: { 5, 10 }