#include <iostream>
#include <string>
using namespace std;
bool solve(string n) {
	if (n == "0") return true;
	if (n[0]=='0') return false;
	for (auto a : n) {
		if (a <= '9'&&'0' <= a) {

		}
		else return false;
	}
	if (0 <= stoi(n)&&stoi(n) <= 12345) return true;
	else return false;
}

int main() {
	string a,b;
	cin >> a >> b;
	if (solve(a) && solve(b)) cout << "OK" << endl;
	else cout << "NG" << endl;
	return 0;
}