A, B = [input().strip() for _ in range(2)]

ans = A.isnumeric() and B.isnumeric()
if ans == True:
  ans = int(A[0]) * int(B[0]) != 0
  A, B = int(A), int(B)
  ans = ans and (A >= 0) and (B >= 0) and (A <= 12345) and (B <= 12345)

print(['NG', 'OK'][ans])