UK spy agency challenges 'wise men and women' to solve Christmas card puzzle

Try your luck at solving the GCHQ Christmas card puzzle.

London (CNN)The UK's largest spy agency GCHQ has sent out its annual Christmas card complete with a brainteaser.

Try and solve the puzzle by completing a series of letter sequences, then fill in your answers on the special Christmas bauble.
"Problem solving is at the heart of what we do. Taking on this Christmas cracker gives puzzlers an insight into the skills you need to be a GCHQ analyst," said a GCHQ spokesperson in a statement published Friday.
    Check GCHQ Twitter and Instagram accounts for the answer to the puzzle.
    "Bring together a mix of minds by sharing it with the wise men and women in your household to find the solution."
      The instructions are as follows: "Complete the following nine sequences and plot your single-letter answers in the corresponding golden nodes on the bauble. Follow the flow of the arrows from somewhere frosty to unlock a message."
      The sequences are: GFEDCB_; NOHHPQ_; MDCLXV_; POIUYT_; DPLLMS_; HHELIB_; NAMWON_; EOEREX_; and GMRDPR_.
      If you want to keep testing your skills, check out the GCHQ Twitter account, which publishes puzzles on a weekly basis.
      The answer to the Christmas puzzle will also be posted on the account, as well as on Instagram and the GCHQ website.