import java.util.*;
class AException extends Exception
{
String a;
AException()
{
a="输入有误";
}
public String toString()
{
return a;
}
}
class A
{
public static void main(String args[])
{
while(1>0)
{
Scanner sc = new Scanner(System.in);
System.out.println("请输入考试成绩（0~100）：");
try
{
String s = sc.nextLine();
getnum(s);
}
catch (AException e)
{
System.out.println(e.toString());
}
}
}
private static void getnum(String s) throws AException
{
for (int i = s.length()-1; i >= 0;i--)
{
int chr = s.charAt(i);
if (chr < 48 || chr > 57)
{
throw new AException();
}
}
double num = Double.parseDouble(s);
if (num < 0 || num> 100)
{
throw new AException();
}
if (num>= 0 && num<= 60)
{
System.out.print("不及格\n");
}
else if (num >= 60 && num <= 70)
{
System.out.print("及格\n");
}
else if (num>= 70 && num<= 80)
{
System.out.print("中\n");
}
else if (num >= 80 && num <= 90)
{
System.out.print("良\n");
}
else
{
System.out.print("优\n");
}
}
}