#include <iostream>
using namespace std;
int main(){
	double a,b;
	cin>>a>>b;
	if(a<35.50&&b<71.00){
		cout<<"AAA"<<endl;
	}else if(a<37.50&&b<77.00){
		cout<<"AA"<<endl;
	}else if(a<40.00&&b<83.00){
		cout<<"A"<<endl;
	}else if(a<43.00&&b<89.00){
		cout<<"B"<<endl;
	}else if(a<50.00&&b<105.00){
		cout<<"C"<<endl;
	}else if(a<55.00&&b<116.00){
		cout<<"D"<<endl;
	}else if(a<70.00&&b<88.00){
		cout<<"E"<<endl;
	}else{
		cout<<"NA"<<endl;
	}
}