#include <bits/stdc++.h>
using namespace std;
int main(){
	int z;
	cin>>z;
	if(z<10){
		cout<<"A";
	}
	if(z>=10&&z<20){
		cout<<"B";
	}
	if(z>=20&&z<40){
		cout<<"C";
	}
	if(z>=40&&z<50){
		cout<<"D";
	}
	if(z>=50&&z<80){
		cout<<"E";
	}
}
/**************************************************************
	Problem: 1044
	User: tonghuawei
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/