#include <iostream>
#include <string>
using namespace std;

string a, b;

bool check(string s) {
	int val = 0;
	
	if (s[0] == '0' && s.length() >= 2) { return false; }
	
	for (int i = 0; i < s.length(); i++) {
		if (!('0' <= s[i] && s[i] <= '9')) { return false; }
		val *= 10;
		val += (s[i] - '0');
	}
	return (val <= 12345);
}

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