#include<iostream>
//#include<math.h>
//#include<stdlib.h>
using namespace std;
int main()
{
    int score,n;
    cin>>score;
    //if(score>0)
    //{
        n=score/10;
        switch(n)
            case 10:
            case 9: cout<<'A';break;
            case 8: cout<<'B';break;
            case 7: cout<<'C';break;
            case 6: cout<<'D';break;
            default: cout<<'E';
    //}
    return 0;
}