#include <iostream>
#include <vector>
#include <string>
#include <array>
#include <queue>
#include <deque>
#include <set>
#include <list>
#include <map>
#include <stack>
#include <utility>
#include <algorithm>
#include <numeric>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cctype>
#include <cstring>
#include <climits>
#include <bitset>
#include <random>
#include <functional>
#include <sstream>
#include <iomanip>

using namespace std;

#define _CRT_SECURE_NO_WARNINGS
#define REP(i, n) for(int i=0; i<(n); i++)
#define FOR(i, m, n) for(int i=(m);i<(n);i++)
#define SZ(x) ((int)(x).size())
#define ALL(x) (x).begin(),(x).end()
#define SORT(x) sort((x).begin(),(x).end())
#define REVE(x) reverse((x).begin(),(x).end())
#define MP make_pair
#define PB push_back

typedef vector<int> VI;
typedef vector<string> VS;
typedef vector<vector<int>> VVI;
typedef pair<int, int> PII;
typedef long long LL;


int main() {
	string a, b;
	cin >> a >> b;
	bool ans = true;
	REP(i, 2) {
		string s = i == 0 ? a : b;
		bool flag = true;
		REP(j, SZ(s))if (!isdigit(s[j]))flag = false;
		if (s[0] == '0'&&SZ(s) >= 2)flag = false;
		if (flag)if (stoi(s) > 12345)flag = false;

		if (!flag)ans = false;
	}
	puts(ans ? "OK" : "NG");
}