#include <iostream>
#include <string>
using namespace std;

int main(void) {
    string s[2];
    cin >> s[0] >> s[1];
    char n[10] = {'0','1','2','3','4','5','6','7','8','9'};
    for (int k=0; k<2; k++){
        for (int i=0; i < s[k].size(); i++) {
            bool checked = false;
            for (int j=0; j < 10; j++) {
                if (s[k][i] == n[j]) {
                    checked = true;
                    break;
                }
            }
            if (s[k].size() > 1 && s[k][0] == '0') checked = false;
            if (!checked) {
                cout << "NG" << endl;
                return 0;
            }
        }
    }
    int ai, bi;
    ai = stoi(s[0]);
    bi = stoi(s[1]);
    if (ai>12345 || ai<0 || bi>12345 || bi<0) {
        cout << "NG" << endl;
    }
    else {
        cout << "OK" << endl;
    }


    return 0;
}