#include<cstdio>
#include<iostream>

using namespace std;

int main() {
    int score;
    while (cin >> score) {
         || score < ) {
            printf("Score is error!\n");
        }
        ) {
            printf("A\n");
        }
        ) {
            printf("B\n");
        }
        ) {
            printf("C\n");
        }
        ) {
            printf("D\n");
        }
        else {
            printf("E\n");
        }
    }
    ;
}