#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<cmath>
#define pi 3.1415927
using namespace std;

int main()
{
    double t;
    while(cin>>t)
    {
        if(t<=100 && t>=90){cout<<"A"<<endl;}
        else if(t<=89 && t>=80){cout<<"B"<<endl;}
        else if(t<=79 && t>=70){cout<<"C"<<endl;}
        else if(t<=69 && t>=60){cout<<"D"<<endl;}
        else if(t<=59 && t>=0){cout<<"E"<<endl;}
        else cout<<"Score is error!"<<endl;
    }
}