#include "bits/stdc++.h"
#include <unordered_set>

#define _CRT_SECURE_NO_WARNINGS

#define FOR(i, x, n) for(decltype(x) i = (x); i < (n); i++)
#define REP(i, n) for(decltype(n) i = 0; i < (n); i++)
#define RREP(i, n) for (decltype(n) i = (n) - 1; i >= 0; i--)

#define ALL(a) (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define DESCSORT(c) sort(c.begin(), c.end(), greater<int>())

using namespace std;

const int dy[] = { 0, 1, 0, -1 };
const int dx[] = { 1, 0, -1, 0 };

using LL = long long int;
using LD = long double;

const int INF = (1 << 30) - 1;
const LL INF64 = ((LL)1 << 62) - 1;
const double PI = 3.1415926535897932384626433832795;

using pii = pair<int, int>;
using pll = pair<LL, LL>;
using pdd = pair<double, double>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vl = vector<LL>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vd = vector<double>;
using vvd = vector<vd>;
using vs = vector<string>;
using vb = vector<bool>;
using vvb = vector<vb>;

bool check(string s) {
	int cnt = 0;
	REP(i, s.size()) {
		if (s[i] == '0') cnt++;
		if (s[i] == '1') cnt++;
		if (s[i] == '2') cnt++;
		if (s[i] == '3') cnt++;
		if (s[i] == '4') cnt++;
		if (s[i] == '5') cnt++;
		if (s[i] == '6') cnt++;
		if (s[i] == '7') cnt++;
		if (s[i] == '8') cnt++;
		if (s[i] == '9') cnt++;
	}

	if (cnt == s.size()) {
		if (stoi(s) < 0 ||12345 < stoi(s)) return false;

		return true;
	} else {
		return false;
	}
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	string a, b;
	cin >> a >> b;

	if (1 < a.size()) {
		if (a[0] == '0') {
			cout << "NG" << endl;
			return 0;
		}
	}
	if (1 < b.size()) {
		if (b[0] == '0') {
			cout << "NG" << endl;
			return 0;
		}
	}

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