#include"stdio.h"
main()
{int a,s;
scanf("%d",&a);
s=a / 10;
switch (s)
{ case 10:printf("A");break;
case 9:printf("A");break;
case 8:printf("B");break;
case 7:printf("C");break;
case 6:printf("D");break;
default:printf("E");break;
}
}