2.1.7 Giac

A grade: { 5, 11, 15, 50 }

B grade: { 1, 2, 3, 4, 6, 7, 8, 9, 13, 19, 20, 26, 28, 30, 34, 35, 48 }

C grade: { 10, 12, 14, 29, 31, 49 }

F grade: { 16, 17, 18, 21, 22, 23, 24, 25, 27, 32, 33, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 51, 52, 53 }