#include <stdio.h>
#include <stdbool.h>

int main(){
	char str1[12346];
	char str2[12346];
	
	int valueflg = true;
	
	int i = 0;
	while(str1[i] != '\0'){
		if(str1[i] <= '0' && str1[i] >= '9'){
			valueflg = false;
		}
	}
	while(str2[i] != '\0'){
		if(str2[i] <= '0' && str2[i] >= '9'){
			valueflg = false;
		}
	}
	if(valueflg == true){
		printf("OK");
	}else{
		printf("NG");
	}
}