#include <stdio.h>
#include <string.h>

int main(void) {
	char s1[6], s2[6];
	int a, b;
	int s1_len, s2_len;
	char s_a[6], s_b[6];
	scanf("%s%s", s1, s2);
	//if(s1[0] == '0' || s2[0] == '0'){
	//	printf("NG\n");
	//	return 0;
	//}
	s1_len = strlen(s1);
	s2_len = strlen(s2);
	a = atoi(s1);
	b = atoi(s2);
	//printf("%d %d\n", a, b);
	sprintf(s_a, "%d", a);
	sprintf(s_b, "%d", b);
	if(strlen(s_a) != s1_len || strlen(s_b) != s2_len){
		printf("NG\n");
		return 0;
	}
	else if((s1_len == 1 && (s1[0] < '0' || s1[0] > '9')) ||
	(s2_len == 1 && (s2[0] < '0' || s2[0] > '9'))){
		printf("NG\n");
		return 0;
	}
	else if(a < 0 || a > 12345 || b < 0 || b > 12345){
		printf("NG\n");
		return 0;
	}
	printf("OK\n");
	
	
	return 0;
}