#include <stdio.h>

int main() {
    int n;
    scanf("%d", &n);
    if (n < 0 || n > 100) {
        printf("Score is error!");
        return 0;
    }
    switch (n / 10) {
        break;
    case 6:
        putchar('D');
        break;
    case 7:
        putchar('C');
        break;
    case 8:
        putchar('B');
        break;
    case 9:
    case 10:
        putchar('A');
        break;
    default:
        putchar('E');
        break;
    }
    return 0;
}