#include<stdio.h>
#include<string.h>
int main()
{
	char a[8], b[8];
	scanf("%s%s", a, b);
	int i, n;
	n = strlen(a);
	for (i = 0; i < n; i++)
	{
		if (a[i] < '0' || '9' < a[i])
		{
			printf("NG\n");
			return 0;
		}
	}
	if (n > 1 && a[0] == '0')
	{
		printf("NG\n");
		return 0;
	}
	n = strlen(b);
	for (i = 0; i < n; i++)
	{
		if (b[i] < '0' || '9' < b[i])
		{
			printf("NG\n");
			return 0;
		}
	}
	if (n > 1 && b[0] == '0')
	{
		printf("NG\n");
		return 0;
	}
	int x = 0;
	n = strlen(a);
	for (i = 0; i < n; i++)
		x = 10 * x + a[i] - '0';
	if (x > 12345)
	{
		printf("NG\n");
		return 0;
	}
	x = 0;
	n = strlen(b);
	for (i = 0; i < n; i++)
		x = 10 * x + b[i] - '0';
	if (x > 12345)
	{
		printf("NG\n");
		return 0;
	}
	printf("OK\n");
	return 0;
}