using System;

public class Program

{

    public static void Main()

    {

        int score = 82;

        char grade ;

        if (score >= 90)

        {

        grade = 'A';

        }

        else if (score >= 80)

        {

        grade = 'B';

        }

        else if (score >= 70)

        {

        grade = 'C';

        }

        else if (score >= 60)

        {

        grade = 'D';

        }

        else

        {

        grade = 'F';

        }

        Console.WriteLine(grade);

    }

}