# coding: utf-8 -*-

import sys


A = input()
B = input()
numbers = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
for i in range(len(A)):
    if (A[i] in numbers) is False or (A[0] == '0' and len(A) != 1):
        print("NG")
        sys.exit()
for i in range(len(B)):
    if (B[i] in numbers) is False or (B[0] == '0' and len(B) != 1):
        print("NG")
        sys.exit()

if 0 <= int(A) <= 12345 and 0 <= int(B) <= 12345:
    print("OK")
else:
    print("NG")