Program hitung_nilai;

uses wincrt;
var
a:integer;
begin
readln(a);
case a of 81..100:writeln ('A');
76..80 :writeln ('AB');
70..75:writeln ('B');
61..70:writeln ('BC');
51..60:writeln ('C');
41..50:writeln ('D');
0..40:writeln ('E');
else writeln('input nilai salah');
end;

end.