#include<bits/stdc++.h>
using namespace std;
int main()
{
	int a;
	char s;
	cin>>a;
	
	if(a<10){
		s='A';
	}else if(a<=20){
     	s='B';
	}else if(a<=40){
    	s='C';
	}else if(a<=50){
    	s='D';
	}else if(a<=80){
    	s='E';
	}
	
	
	printf("%c",s);
	
	
	
	
	return 0;
}

/**************************************************************
	Problem: 1044
	User: czr
	Language: C++
	Result: Wrong Answer
****************************************************************/