#include <iostream>
using namespace std;
int main()
{
    double grade;
    cin>>grade;
    switch(grade/10)
    {
        case 10:
        case 9:
        {cout<<"A"<<endl;break;
        }
        case 8:
            {
                cout<<"B"<<endl;break;
            }
        case 7:
            {
                cout<<"C"<<endl;break;
            }
        case 6:
            {
                cout<<"D"<<endl;break; 
            }
        default:
           {
               cout<<"E"<<endl; 
           }
    }
 }