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

int main()
{
int i;
char S[ 100 ];
char A[ 10 ];
char B[ 10 ];

	cin >> A;
	cin >> B;

	do
	{
		if( A[ 0 ] < '0' || A[ 0 ] > '9' ) break;

		sscanf( A, "%d", &i );
		if( i > 12345 ) break;
		if( sprintf( S, "%d", i ) < strlen( A ) ) break;

		if( B[ 0 ] < '0' || B[ 0 ] > '9' ) break;

		sscanf( B, "%d", &i );
		if( i > 12345 ) break;
		if( sprintf( S, "%d", i ) < strlen( B ) ) break;

		cout << "OK" << endl;

		return 0;
	}
	while( false );

	cout << "NG" << endl;

	return 0;
}