# include <iostream>
# include <algorithm>
# include <vector>
# include <string>
# include <set>
# include <map>
# include <cmath>
# include <iomanip>
# include <functional>
# include <utility>
# include <stack>
# include <queue>
# include <list>
# include <tuple>
# include <unordered_map>
# include <numeric>
# include <complex>
# include <bitset>
# include <random>
# include <chrono>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
typedef pair<LL, LL> P;
constexpr int INF = 2147483647;
constexpr int HINF = INF / 2;
constexpr double DINF = 100000000000000000.0;
constexpr long long LINF = 9223372036854775807;
constexpr long long HLINF = 4500000000000000000;
const double PI = acos(-1);
int dx[4] = { 0,1,0,-1 }, dy[4] = { 1,0,-1,0 };
# define ALL(x)      (x).begin(),(x).end()
# define UNIQ(c)     (c).erase(unique(ALL((c))),(c).end())
# define mp          make_pair
# define eb          emplace_back
# define FOR(i,a,b)  for(int i=(a);i<(b);i++)
# define RFOR(i,a,b) for(int i=(a);i>=(b);i--)
# define REP(i,n)    FOR(i,0,n)
# define INIT        std::ios::sync_with_stdio(false);std::cin.tie(0)

string a, b;
bool isok = true;
int main() {
	cin >> a >> b;
	REP(i, a.size())if (!('0' <= a[i] && a[i] <= '9'))isok = false;
	REP(i, b.size())if (!('0' <= b[i] && b[i] <= '9'))isok = false;
	if (!isok) {
		cout << "NG" << endl;
		return 0;
	}
	int aa = stoi(a);
	int bb = stoi(b);
	if (aa > 12345 || bb > 12345)isok = false;
	if (aa < 10000 || bb < 10000)isok = false;
	if (!isok) {
		cout << "NG" << endl;
	}
	else {
		cout << "OK" << endl;
	}
}