#include <stdio.h>

int main() {
int S,t;
scanf("%d",&S);
t= S/10;
if(S==100){
    printf("A");
}
else{
       switch(t){
           case 9:
           printf("A");
           break;
           case 8:
           printf("B");
           break;
           case 7:
           printf("C");
           break;
           case 6:
           printf("D");
           break;
           case 0:
           case 1:
           case 2:
           case 3:
           case 4:
           case 5:
           printf("E");
           break;
           default:
           printf("EORR");
}
}
return 0;
｝
//哈基米