François Hollande, famous Cordon Bleu chef that he (like all French presidents) is, has invited a select few guests to his party, where he will be showing off the secret cheese-making process that doubles as a plan of attack against Britain. Your task as a UK spy (who happens to also be an Argentinian agent) is to steal this recipe for disaster. Entrance to the château wherein lies the party, however, is overseen by two guards. One guard always lies, and the other always tells the truth.

You arrive early and hide in some bushes. Guests begin approaching the door, and it becomes clear that there is some kind of password involved.

  • One guest arrives by himself. “1”, says a guard. “6”, replies the guest. He is permitted entrance.
  • Two more guests show up. “3” is prompted; “2” is the response, and it is apparently correct.
  • A group of seven is next to request entry, and the guards see fit to ask them each in turn.

    • “2!” “7.”
    • “11!” “6.”
    • “20!” “4.”
    • “4!” “2.”
    • “6!” “3.”

    The group had been doing fine until that last person, whose throat is promptly slit, along with those of what look to be his wife and son. “You were just off by one!”, says one of the guards, who looks like the sort of person who would tell the truth – but then again, it’s hard to tell with them. You’re not in Argentina anymore.

You think you’ve figured out the pattern, though, and are about to take your turn when another guest arrives, late. The challenge is given – “26” – but before the guest can give an answer, a loud gunshot is heard. Someone shouts out the window that the president is dead! It’s a coup d’état! You must get to the plans before the assassin, but one guard is still performing his duty. You are given the number five as a challenge; what is your response?

  • 1
    $\begingroup$ What a story........ looks like Homeland in medieval times..;) $\endgroup$ Nov 13, 2014 at 7:45
  • $\begingroup$ Are the Argentina references and the president's murder hints or just extra red-herring details? $\endgroup$ Nov 15, 2014 at 18:57
  • $\begingroup$ @randal'thor: References to other puzzles on the site. The Argentina ones don’t matter, no. $\endgroup$
    – Ry-
    Nov 16, 2014 at 16:36
  • $\begingroup$ To clarify "until that last person" - does this mean that responding "3" to the guard's "6" is incorrect? Or is the interaction of this last person omitted from the list? $\endgroup$
    – Leo
    Nov 19, 2014 at 21:20
  • $\begingroup$ @Leo: Yes, it means that responding “3” to “6” is incorrect. $\endgroup$
    – Ry-
    Nov 20, 2014 at 21:05

2 Answers 2


The answer is


The rule is

If the number that the guard tells you is n, respond with the number of letters in the nth word of The French National Anthem (in French, of course).

Here is the first stanza:

French lyrics
Allons enfants de la Patrie,
Le jour de gloire est arrivé !
Contre nous de la tyrannie,
L'étendard sanglant est levé, (bis)
Entendez-vous dans les campagnes
Mugir ces féroces soldats ?
Ils viennent jusque dans nos bras
Égorger nos fils, nos compagnes !

All of the words match, and the incorrect answer (off by one) fits as well!

enter image description here

  • 1
    $\begingroup$ The response to 3 was 2, not 6. So no typo. $\endgroup$
    – mmking
    Jun 12, 2015 at 21:21
  • $\begingroup$ This is it! Well done. $\endgroup$
    – Ry-
    Jun 12, 2015 at 22:28
  • 1
    $\begingroup$ I wish I could upvote this 20 times, so glad it finally got answered! Great job JLee $\endgroup$
    – alexmc
    Jun 13, 2015 at 4:17
  • $\begingroup$ @alexmc Thanks! I had never seen this puzzle til yesterday. I don't know how I missed it. I just got lucky. The French National Anthem (which I didn't even know existed til I Googled it) was my first idea. Surprising I got it, because I'm usually better at creating puzzles, rather than solving them. $\endgroup$
    – JLee
    Jun 13, 2015 at 11:49

I'm guessing the answer is 0. All the answers are to have an implicit relation with number 5.

1 - 6 = 5 | 3 + 2 = 5| 2 - 7 = 5| 11 - 6 = 5| 20 / 4 = 5

But the last two was not so. As the last person is found wrong but the one before that is not means that guest was questioned by the guard who speaks lies and the last guest was questioned by the guard who speaks truth.

   “You were just off by one!”, says one of the guards who looks like the sort of person who would tell the truth – but then again, it’s hard to tell with them.

This means that what the guard told was a lie.

  • $\begingroup$ And the 4 and 2? $\endgroup$ Nov 21, 2014 at 14:01
  • $\begingroup$ Also, the respond to answering '3' to '6!' was that its only one off. 6 and 2 do not make 5 in any sense and neither do 6 and 4 (unless you take the average but that is a stretch). $\endgroup$
    – Leo
    Nov 21, 2014 at 14:06
  • $\begingroup$ @quy : That might have been asked by the guard who lies. $\endgroup$
    – mani_nz
    Nov 21, 2014 at 14:48
  • $\begingroup$ @Leo: '3' to '6!' was that its only one off, said by a guard who could be lying. Read it again. It says he could tell the truth but not sure $\endgroup$
    – mani_nz
    Nov 21, 2014 at 14:50
  • $\begingroup$ @mani_nz the OP already said in a previous comment that the lie/truth aspect has no bearing on the puzzle and that it is just a reference. In the event that it DID have a bearing on the puzzle we could just pick and choose which Q&A examples we want to use to fit an operation <- this would not make sense as it would make the solution too loose. $\endgroup$
    – Leo
    Nov 21, 2014 at 15:10

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