6

#include<bits/stdc++.h>
using namespace std;
int a;
int main(){
cin>>a;
if(a>=90&&a<=100){
cout<<'A';
}else if(a>=80&&a<=98){
cout<<'B';
}else if(a>=70&&a<=79){
cout<<'C';
}else if(a>=60&&a<=69){
cout<<'D';
}else{
cout<<'E';
}
return 0;
}