include

using namespace std; int main() {

int n;
cin>>n;
if(n>=90&&n<=100)cout<<"A";
	else if(n>=80&&n<90)cout<<"B";
		else if(n>=70&&n<80)cout<<"C";
			else if(n>=60&&n<70)cout<<"D";
				else if(n>=0&&n<60)cout<<"E";
return 0;

}