#include<bits/stdc++.h>
using namespace std;
int x;
int main(){
	cin>>x;
	x/=10;
	switch(x){
	case 0: cout<<"A";break;
	case 1: cout<<"B";break;
	case 2: case 3:cout<<"C";break;
	case 4: cout<<"D";break;
	default: cout<<"E";
}	
	return 0;
}

/**************************************************************
	Problem: 1044
	User: zhangziang
	Language: C++
	Result: Accepted
	Time:13 ms
	Memory:2072 kb
****************************************************************/