#include <bits/stdc++.h>
using namespace std;
int main()
{
    int a;
    cin>>a;
    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: ccf
	Language: C++
	Result: Compile Error
****************************************************************/