# coding: utf-8

def valid(s):
    for c in s:
        o = ord(c)
        if not (ord("0") <= o and o <= ord("9")):
            return False
    if s[0] == "0" and len(s) > 1:
        return False
    i = int(s)
    if i > 12345:
        return False
    return True

a = input().strip()
b = input().strip()
if valid(a) and valid(b):
    print("OK")
else:
    print("NG")