#include <iostream>
using namespace std;
int main(){
	double a,b;
	cin>>a>>b;
	if(a<35.5&&b<71.0){
		cout<<"AAA"<<endl;
	}else if(a<37.5&&b<77.0){
		cout<<"AA"<<endl;
	}else if(a<40.0&&b<83.0){
		cout<<"A"<<endl;
	}else if(a<43.0&&b<89.0){
		cout<<"B"<<endl;
	}else if(a<50.0&&b<105.0){
		cout<<"C"<<endl;
	}else if(a<55.0&&b<116.0){
		cout<<"D"<<endl;
	}else if(a<70.0&&b<88.0){
		cout<<"E"<<endl;
	}else{
		cout<<"NA"<<endl;
	}
}