#include<bits/stdc++.h>
#define INF 0x3f3f3f3f
#define rep(i,n)for(int i=0;i<n;i++)
using namespace std;
typedef long long ll;
typedef pair<int, int>P;

bool func(string a) {
	if (a.size() < 5)return true;
	return a <= "12345";
}
int main() {
	string a, b; cin >> a >> b;
	if ((a.size()!=1&&*a.begin() == '0') ||(b.size()!=1&& *b.begin() == '0')) {
		puts("NG"); return 0;
	}
	for (char c : a) {
		if (isalpha(c)) {
			puts("NG"); return 0;
		}
	}
	for (char c : b) {
		if (isalpha(c)) {
			puts("NG"); return 0;
		}
	}
	puts(func(a) && func(b) ? "OK" : "NG");
}