#include<stdio.h>
#include<stdlib.h>
#include<string.h>
main(){
    char A[6],B[6];
    scanf("%s %s",A,B);
    for(int i = 0;i < strlen(A);i++){
        if(A[i] < '0' || A[i] > '9'){
            printf("NG\n");
            return 0;
        }
    }
    for(int i = 0;i < strlen(B);i++){
        if(B[i] < '0' || B[i] > '9'){
            printf("NG\n");
            return 0;
        }
    }
    if(A[1]!='\0'&&A[0]=='0'){
        printf("NG\n");
        return 0;
    }
    if(B[1]!='\0'&&B[0]=='0'){
        printf("NG\n");
        return 0;
    }
    if(atoi(A) < 0 || atoi(A) > 12345){
        printf("NG\n");
        return 0;
    }
    if(atoi(B) < 0 || atoi(B) > 12345){
        printf("NG\n");
        return 0;
    }
    printf("OK\n");
}