C :

#include<stdio.h>
int main()
{
 int grade;
 while(scanf("%d",&grade)!=EOF)
 {
   grade/=10;
   switch(grade)
   { 
    case 10:printf("A\n");break;
    case 9:printf("A\n");break;
    case 8:printf("B\n");break;
    case 7:printf("C\n");break;
    case 6:printf("D\n");break;
    default:printf("E\n");break;
   }
 }

 
}

C++ :

#include<stdio.h>
char f(int x){
  if(x<60) return 'E';
  if(x>=60&&x<70) return 'D';
  if(x>=70&&x<80) return 'C';
  if(x>=80&&x<90) return 'B';
  return 'A';
}
int main(){
  int a;
  scanf("%d",&a);
  printf("%c",f(a));
  return 0;
}

Java :

import java.util.Scanner;

public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner input = new Scanner(System.in);
		int Score = input.nextInt();
		switch(Score/10){
		    case 10: ;
		    case 9:System.out.println('A');break;
		    case 8:System.out.println('B');break;
		    case 7:System.out.println('C');break;
		    case 6:System.out.println('D');break;
		    default:System.out.println('E');break;
		}
	}

}

Python :

a=(raw_input())
if(a>=90):
    print 'A'
elif(a>=80):
    print 'B'
elif(a>=70):
    print 'C'
elif(a>=60):
    print 'D'
else:
    print 'E'