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

int main(){
	char a, b;
	cin >> a;
	cin >> b;
	int a2 = (int)a;
	int b2 = (int)b;
	if(a2 >=0 && a2 <= 12345 && 0 <= b2 && b2 <= 12345){
		cout << "OK" << endl;
	}else{
		cout << "NG" << endl;
	}
	return 0;

}