#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	cin>>n;
	n/=10;
	switch(n)
	{
		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: tangkaixuan
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/