#include <bits/stdc++.h>
using namespace std;

int main()
{
	string A, B;
	cin >> A >> B;

	string ans = "OK";
	int a = 0;
	for( int i = 0; i < A.size(); i++ ) {
		if( isdigit( A[i] ) == false ) {
			ans = "NG";
			break;
		}
		a = a * 10 + A[i] - '0';
	}
	if( ans == "OK" ) {
		if( (a || A.size() > 1) && A[0] == '0' ) ans = "NG";
		if( a > 12345 ) ans = "NG";
		int b = 0;
		for( int i = 0; i < B.size(); i++ ) {
			if( isdigit( B[i] ) == false ) {
				ans = "NG";
				break;
			}
			b = b * 10 + B[i] - '0';
		}
		if( ans == "OK" ) {
			if( (b || B.size() > 1) && B[0] == '0' ) ans = "NG";
			if( b > 12345 ) ans = "NG";
		}
	}

	cout << ans << endl;
}