#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstdlib>
using namespace std;

int main()
{
	string a, b; cin >> a >> b;
	bool flag = false;
	if (a.size()!=1 && a[0] == '0')flag = true;
	for (int i = 0; i < a.size(); i++) {
		if (a[i] < 48 || a[i]>57)flag = true;
	}
	if (!flag) {
		int na = atoi(a.data());
		if (na > 12345)flag = true;
	}
	if (b.size()!=1 && b[0] == '0')flag = true;
	for (int i = 0; i < b.size(); i++) {
		if (b[i] < 48 || b[i]>57)flag = true;
	}
	if (!flag) {
		int nb = atoi(b.data());
		if (nb > 12345)flag = true;
	}
	if (flag)cout << "NG" << endl;
	else cout << "OK" << endl;

    return 0;
}