2.1.6 Sympy

A grade: { 4, 8, 12, 21 }

B grade: { }

C grade: { }

F grade: { 1, 2, 3, 5, 6, 7, 9, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, 26, 27, 28, 29 }