In this puzzle, we only consider independent countries and we do not count overseas territories as actual part of a country. We say that three countries form a well-connected triple, if each pair shares a piece of common border with strictly positive length. Most of these well-connected triples furthermore meet at a point (at least theoretically).

Q: What are the twelve well-connected triples that do not have any common point that is shared by all three countries?

  • $\begingroup$ I have corrected my question from ten to twelve triples. I had overlooked the two triples with Turkey. The "correct answer" sign goes to Christopher Fish who found the last two (and hence hardest) answers. $\endgroup$
    – Alexis
    Commented Feb 12, 2015 at 13:28

3 Answers 3


Two more as yet unmentioned:

  • Armenia, Iran, Turkey
  • Croatia, Montenegro, Serbia

By my count this makes 12, not counting the dubious borders-in-lakes ones.


There are a number of possible triples with Russia, thanks to Kaliningrad Oblast. You may wish to exclude this, even though it is not an overseas territory, and it is an oblast (roughly, a state or province) of Russia.

  • Russia, Poland, Belarus
  • Russia, Poland, Ukraine
  • Russia, Lithuania, Belarus
  • Russia, Lithuania, Latvia

Another, possibly more "legitimate" answer not yet given is

  • Tanzania, Malawi, Mozambique
  • $\begingroup$ I find it really odd that you want to discount ones involving the Kaliningrad Oblast, yet count one where the only sense in which there isn't a common point is that it's in the middle of a lake. $\endgroup$ Commented Feb 11, 2015 at 16:27
  • $\begingroup$ @ChristopherFish I don't want to discount them, I just didn't know if the OP intended to allow them. $\endgroup$
    – KSmarts
    Commented Feb 12, 2015 at 14:40

Some quick and easy answers:

  1. France, Germany, Belgium
  2. Brazil, Argentina, Bolivia
  3. Congo, Tanzania, Uganda
  4. Congo, Tanzania, Rwanda
  5. Tanzania, Mozambique, Zambia
  6. Turkey, Georgia, Azerbaijan
  • $\begingroup$ Kenya, Uganda, Tanzania $\endgroup$
    – dmg
    Commented Feb 11, 2015 at 13:56
  • $\begingroup$ @dmg: But Kenya, Uganda, Tanzania share a common point somewhere in the middle of Lake Victoria... $\endgroup$
    – Gamow
    Commented Feb 11, 2015 at 14:08
  • $\begingroup$ I guess it depends on the interpretation of borders. Lakes are often considered the end of the territory of a country, rather than some line going through the lake. $\endgroup$
    – dmg
    Commented Feb 11, 2015 at 14:15
  • $\begingroup$ But this is not the case with Lake Victoria. $\endgroup$
    – Gamow
    Commented Feb 11, 2015 at 14:17

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.