#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
	cin>>n;
	     if(n<10) cout<<'A';
	else if(n>=10&&n<20) cout<<'B';
	else if(n>=20&&n<40) cout<<'C';
	else if(n>=40&&n<50) cout<<'D';
	else cout<<'E';


}

/**************************************************************
	Problem: 1044
	User: fandaohan
	Language: C++
	Result: Accepted
	Time:28 ms
	Memory:2072 kb
****************************************************************/