#include <bits/stdc++.h>
using namespace std;
int main(){
    int i;
    cin>>i;
    if(i<10)cout<<'A';
    else if(i<20)cout<<'B';
    else if(i<40)cout<<'C';
    else if(i<50)cout<<'D';
    else cout<<'E';
    return 0;
}
/**************************************************************
	Problem: 1044
	User: baizhoudeyueguang
	Language: C++
	Result: Accepted
	Time:15 ms
	Memory:2072 kb
****************************************************************/