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

int main(void) {
    string s[2];
    cin >> s[0] >> s[1];
    int 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[i]+'0') {
                    checked = true;
                    break;
                }
            }
            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;
}