import java.util.Scanner;


public class Bathmos2
{

    public static void main(String[] args)
    {
      getInput();

    }
    public static void getInput()
    {
        int x;
        Scanner input = new Scanner(System.in);
        System.out.println("Give your grade: ");
        x = input.nextInt();
        int grade = gradeToInt(x);
        switch (grade)
        {
         case 1:
             System.out.println("U got an A");
             break;
         case 2:
             System.out.println("U got a B");
             break;
         case 3:
             System.out.println("U got a C");
             break;
         case 4:
             System.out.println("U got a D");
             break;
         case 5:
             System.out.println("U got an F");
             break;
         case 6:
             System.out.println("Invalid entry, please try again");
             getInput();
             break;
        }
    }
 public static boolean inRange(int value, int min, int max)
 {
  return (value>=min)&&(value<max);
 }

 public static int gradeToInt(int x)
 {
  int   output = 1;
  int[] gradeA = {1, 90, 101};
  int[] gradeB = {2, 80, 90};
  int[] gradeC = {3, 70, 80};
  int[] gradeD = {4, 60, 70};
  int[] gradeF = {5, 0, 60};


  int[][] grades = {gradeA,gradeB,gradeC,gradeD,gradeF};

  int i = 0;
  boolean s = false;
  try
  {
    while( s == false)
    {
    output = grades[i][0];
     s = inRange(x, grades[i][1], grades[i][2]);
    i = i + 1;
    }
    return output;
  }
  catch (IndexOutOfBoundsException e)
  {
      return 6;
  }
  }

 }