include<bits/stdc++.h>

using namespace std; int main(){

int n;
cin>>n;
if(n<=100&&n>=90){cout<<"A";}
if(n<=89&&n>=80){cout<<"B";}
if(n<=79&&n>=70){cout<<"C";}
if(n<=69&&n>=60){cout<<"D";}
if(n<=59&&n>=0){cout<<"E";}
return 0;

}