#include <bits/stdc++.h>
using namespace std;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	string a, b;
	cin >> a >> b;
	for(int i = 0; i < a.size(); i++) {
		if(a[i] < '0' || a[i] > '9') {
			cout << "NG" << endl;
			return 0;
		}
	}
	for(int i = 0; i < b.size(); i++) {
		if(b[i] < '0' || b[i] > '9') {
			cout << "NG" << endl;
			return 0;
		}
	}
	bool nzero = false;
	for(int i = 0; i < a.size(); i++) {
		if(!nzero && a[i] == '0') {
			if(a == "0") break;
			cout << "NG" << endl;
			return 0;
		}
		if(b[i] != '0') nzero = true;
	}
	nzero = false;
	for(int i = 0; i < b.size(); i++) {
		if(!nzero && b[i] == '0') {
			if(b == "0") break;
			cout << "NG" << endl;
			return 0;
		}
		if(b[i] != '0') nzero = true;
	}
	int x = stoi(a), y = stoi(b);
	if(x > 12345 || x < 0) {
		cout << "NG" << endl;
		return 0;
	}
	if(y > 12345 || y < 0) {
		cout << "NG" << endl;
		return 0;
	}
	cout << "OK" << endl;
	return 0;	
}