#include <bits/stdc++.h>

using namespace std;
 
int cnt_500(double f)
{
    if (f < 35.5) return 1;
    else if (f < 37.5) return 2;
    else if (f < 40) return 3;
    else if (f < 43) return 4;
    else if (f < 50) return 5;
    else if (f < 55) return 6;
    else if (f < 70) return 7; 
    return 8;
}
 
int cnt_1000(double t)
{
    if (t < 71) return 1;
    else if (t < 77) return 2;
    else if (t < 83) return 3;
    else if (t < 89) return 4;
    else if (t < 105) return 5;
    else if (t < 116) return 6;
    else if (t < 148) return 7;  
    return 8;
}
 
int main()
{
    double f, t;
    while (cin >> f >> t) {
        int grade = max(cnt_500(f), cnt_1000(t));
        switch (grade) { 
            case 1:
                cout << "AAA" << endl;
                break;
            case 2:
                cout << "AA" << endl;
                break;
            case 3:
                cout << 'A' << endl;
                break;
            case 4:
                cout << 'B' << endl;
                break;
            case 5:
                cout << 'C' << endl;
                break;
            case 6:
                cout << 'D' << endl;
                break;
            case 7:
                cout << 'E' << endl;
                break;
            case 8:
                cout << "NA" << endl;
                break;
        } 
    }
    return 0;
}