#include <iostream>
using namespace std;

int main() {
    int weight;
    cin >> weight;
    char box_type;
    if (weight < 10) {
        box_type = 'A';
    } else if (weight < 20) {
        box_type = 'B';
    } else if (weight < 40) {
        box_type = 'C';
    } else if (weight < 50) {
        box_type = 'D';
    } else if (weight < 80) {
        box_type = 'E';
    }
    cout << box_type << endl;
    return 0;
}    
/**************************************************************
	Problem: 1044
	User: fuyijun
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/