#include <iostream>
#include <cstdio>
#include <vector>
#include <cmath>
#include <cstring>
#include <numeric>
#include <algorithm>
#include <functional>
#include <array>
#include <map>
#include <queue>
#include <limits.h>
#include <set>
#include <stack>
#include <random>
#define rep(i,s,n) for(int i = (s); (n) > i; i++)
#define REP(i,n) rep(i,0,n)
#define RANGE(x,a,b) ((a) <= (x) && (x) <= (b))
#define DUPLE(a,b,c,d) (RANGE(a,c,d) || RANGE(b,c,d) || RANGE(c,a,b) || RANGE(d,a,b))
#define INCLU(a,b,c,d) (RANGE(a,c,d) && (b,c,d))
#define POWT(x) ((x)*(x))
#define ALL(x) (x).begin(), (x).end()
#define MODU 1000000007
#define bitcheck(a,b)   ((a >> b) & 1)
#define bitset(a,b)      ( a |= (1 << b))
#define bitunset(a,b)    (a &= ~(1 << b))
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;

const pii Dir[8] = { //?????????
	{ 0,1 },{ 0,-1 },{ 1,0 },{ -1,0 },
	{ 1,1 },{ 1,-1 },{ -1,-1 },{ -1,1 }
};
template<typename A, size_t N, typename T>
void Fill(A(&array)[N], const T &val) {
	std::fill((T*) array, (T*) (array + N), val);
}

signed main() {
	REP(cc, 2) {
		char str[6];
		scanf("%s", str);
		bool f = 0;
		if (str[0] != '0') {
			bool f2 = 1;
			REP(i, strlen(str)) {
				if (!RANGE(str[i], '0', '9')) {
					f2 = 0;
					break;
				}
			}
			if (f2) {
				int num = atoi(str);
				if (num <= 12345)
					f = 1;
			}
		}
		else if (str[0] == '0' && strlen(str) == 1) {
			f = 1;
		}
		if (!f) {
			printf("NG\n");
			return 0;
		}
	}
	printf("OK\n");
	return 0;
}