#include <iostream>
using namespace std;

int main() {
	int n;
	cin >> n;
	switch (n / 10) {
	case 10:
		cout << "A" << endl;
		break;
	case 9:
		cout << "A" << endl;
		break;
	case 8:
		cout << "B" << endl;
		break;
	case 7:
		cout << "C" << endl;
		break;
	case 6:
		cout << "D" << endl;
		break;
	default:
		cout << "E" << endl;
		break;
	}
	return 0;
}