Sympy

A grade

{ 9, 10, 11 }

B grade

{ 3, 12 }

C grade

{ }

F normal fail

{ 4, 5, 8, 18, 19, 20 }

F(-1) timedout fail

{ 1, 2, 6, 7, 13, 14, 15, 16, 17 }

F(-2) exception fail

{ }