Var x:real;
begin 
Write(' nhap diem:'); readln(n);
If (n>=3.5) and ( n<=4.9) then write ('yeu') else
If (n>=5) and ( n<=6.4) then write ( 'tb') else
If (n>=5) and ( n<=7.9) then write('kha') else 
If (n>=8) and ( n<=10 ) then write(' gioi');
Readln
End.