from string import ascii_letters
ng = set(ascii_letters)

def check(S):
    if S == "0":
        return True
    if not set(S).isdisjoint(ng):
        return False
    if S[0] == "0":
        return False
    return int(S) <= 12345

ans = check(input()) & check(input())
if ans:
    print("OK")
else:
    print("NG")