2.1.6 Sympy

A grade: { }

B grade: { 1, 2, 3, 4, 9, 10, 11, 17, 18 }

C grade: { 5, 6, 12, 19, 21, 22, 23, 24, 25, 31, 32 }

F grade: { 7, 8, 13, 14, 15, 16, 20, 26, 27, 28, 29, 30, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46 }