#define _USE_MATH_DEFINES

#include <iostream>		//cin, cout
#include <vector>		//vector
#include <algorithm>	//sort,min,max,count
#include <string>		//string,getline, to_string
#include <cstdlib>		//abs(int)
#include <utility>		//swap, pair
#include <tuple>        //tuple
#include <deque>		//deque
#include <climits>		//INT_MAX
#include <bitset>		//bitset
#include <cmath>		//sqrt, ceil. M_PI, pow, sin
#include <ios>			//fixed
#include <iomanip>		//setprecision
#include <sstream>		//stringstream
#include <numeric>		//gcd, assumlate
#include <random>		//randam_device
#include <limits>		//numeric_limits
#include <functional>

using namespace std;
constexpr long long int D_MOD = 1000000007;

int main() {

	string A, B;
	cin >> A >> B;

	bool flg = true;

	if (A.size() > 5) { flg = false; }

	if (flg && B.size() > 5) { flg = false; }
	
	if (flg) {
		for (unsigned int i = 0; i < A.size(); i++) {
			if (A.at(i) < '0' || '9' < A.at(i)) {
				flg = false;
				break;
			}
		}
	}

	if (flg) {
		for (unsigned int i = 0; i < B.size(); i++) {
			if (B.at(i) < '0' || '9' < B.at(i)) {
				flg = false;
				break;
			}
		}
	}

	if (flg) {
		int a = stoi(A);
		if (a < 0 || 12345 < a) {
			flg = false;
		}
	}

	if (flg) {
		int b = stoi(B);
		if (b < 0 || 12345 < b) {
			flg = false;
		}
	}

	if (flg) {
		cout << "OK" << endl;
	}
	else {
		cout << "NG" << endl;
	}

	return 0;

}