# -*- coding: utf-8 -*-
"""
No.446 ゆきこーだーの雨と雪 (1)
https://yukicoder.me/problems/no/446

"""
import sys
from sys import stdin
input = stdin.readline


def solve(A, B):
    try:
        num_a = int(A)
        num_b = int(B)
    except:
        return 'NG'

    if not 0 <= num_a <= 12345:
        return 'NG'
    if not 0 <= num_b <= 12345:
        return 'NG'
    if num_a == 0 and len(A) > 1:
        return 'NG'
    if num_b == 0 and len(B) > 1:
        return 'NG'
    if A[0] == '0' and num_a != 0:
        return 'NG'
    if B[0] == '0' and num_b != 0:
        return 'NG'

    return 'OK'


def main(args):
    A = input().strip()
    B = input().strip()
    ans = solve(A, B)
    print(ans)


if __name__ == '__main__':
    main(sys.argv[1:])