#include <bits/stdc++.h>

using namespace std;

#define REP(i, n) for(int i = 0; i < n; i++)

int main() {
    vector<string> vs(2);
    cin >> vs[0] >> vs[1];
    REP(i, 2) {
        REP(j, vs[i].length()) {
            if ('0' <= vs[i][j] && vs[i][j] <= '9') continue;
            else {
                cout << "NG" << endl;
                return 0;
            }
        }

        if (vs[i].length() != 1 && vs[i][0] == '0') {
            cout << "NG" << endl;
            return 0;
        }

        if (stoi(vs[i]) > 12345 || stoi(vs[i]) < 0) {
            cout << "NG" << endl;
            return 0;
        }
    }
    cout << "OK" << endl;
    return 0;
}