#include<cstdio>
#include <iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>

#define mod 1000000007;

using namespace std;
typedef long long ll;
typedef pair<ll, ll> Pr;

string A, B;

int main()
{
	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;
		}
	}
	
	int len_a = A.size(), len_b = B.size();
	string num_a = to_string(stoi(A)), num_b = to_string(stoi(B));
	
	if (len_a != num_a.size() || len_b != num_b.size() || stoi(num_a) > 12345 || stoi(num_b) > 12345) {
		cout << "NG" << endl;
	}
	else
		cout << "OK" << endl;
	return 0;
}