#include<iostream>
#include<algorithm>
#include<string>
using namespace std;
#define MAX_CLASS 8

int check(double m, int type);

int main(){
    double m500, m1000;
    string cls[MAX_CLASS] = {"AAA", "AA", "A", "B", "C", "D", "D", "NA"};
    while(cin >>m500 >>m1000){
        cout <<cls[max(check(m500, 0), check(m1000, 1))] <<endl;
    }
    return 0;
}

int check(double m, int type){
    double dx[2][MAX_CLASS] = {{35.5, 37.5, 40.0, 43.0, 50.0, 55.0, 70.0}, {71.0, 77.0, 83.0, 89.0, 105.0, 116.0, 148.0}};
    int ret = 7;
    for(int i = 0; i < MAX_CLASS; i++){
        if(m < dx[type][i]){
            ret = i;
            break;
        }
    }
    return ret;
}