#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	cin>>n;
	if(n<10) cout<<"A";
	else if(n<20) cout<<"B";
		 else if(n<40) cout<<"C";
	          else if(n<50) cout<<"D";
                   else if(n<80) cout<<"E";



	return 0;
}

/**************************************************************
	Problem: 1044
	User: 21A
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/