#include<stdio.h>
main()
{ int n,t;
printf("Input the score:");
scanf("%d",&n);
printf("\n");
if(n==100)
printf("A");
else
{if(0<=n&&n<60)t=5;
else t=n/10;
switch(t)
{case 9:printf("A");break;
case 8:printf("B");break;
case 7:printf("C");break;
case 6:printf("D");break;
case 5:printf("E");break;
default:printf("error");
}}}