#include <iostream>
#include <string>

using namespace std;
int main()
{
	string s[2];
	int cknum[2];
	bool flag = false;
	cin >> s[0] >> s[1];
	for (int i = 0; i < 2; i++)
	{
		for (int j = 0; j < s[i].length(); j++)
		{
			if (!(s[i].at(j) >= 48 && s[i].at(j) <= 57)) flag = true;
		}

		if (s[i].size() >= 2 && s[i].at(0) == '0') flag = true;
		
		if (!flag)
		{
			cknum[i] = stoi(s[i]);

			if (cknum[i] > 12345) flag = true;
		}
	}

	cout << (flag ? "NG" : "OK") << endl;
	return 0;
}