#include <iostream>
using namespace std;

int main(){
	string a, b;
	cin >> a >> b;
	int aa = 0, bb = 0;
	bool f = a != "0";
	for(char c:a){
		if(!isdigit(c) || (f && c == '0')){
			cout << "NG" << endl;
			return 0;
		}
		f &= c - '0' == 0;
		aa *= 10;
		aa += c - '0';
	}
	f = b != "0";
	for(char c:b){
		if(!isdigit(c) || (f && c == '0')){
			cout << "NG" << endl;
			return 0;
		}
		f &= c - '0' == 0;
		bb *= 10;
		bb += c - '0';
	}
	cout << (0 <= aa && aa <= 12345 && 0 <= bb && bb <= 12345 ? "OK" : "NG") << endl;
}