#include <future>
#include <iostream>
using namespace std;
int main(){
    int a;
    cin>>a;
    int b=a/10;
    switch (b) {
        case 10:
            cout<<"A";
            break;
        case 9:
            cout<<"A";
            break;
        case 8:
            cout<<"B";
            break;
        case 7:
            cout<<"C";
            break;
        case 6:
            cout<<"D";
            break;
        default:
            cout<<"E";
    }
    return 0;
}