The 12 coins 12 coins problem but you can't understand the scale asks for is not the maximum possible, therefor this follow-up question:
You have a number of coins, one is fake but you don't know if it is lighter or heavier. You have a scale that gives you output but you don't understand it (let's say it is written in a foreign language that you don't understand).
For each possible answer (left, right, equal) there is only one output. Let's say you put 2 coins on the scale and the left is heavier, it A will be presented on the scale. But you see only A which you can't derive that it means that left is heavier because it is in some foreign language that you don't understand. But - A will be always if left is heavier, B for if right is heavier and C if it is equal, you'll just won't know it when you'll see the output.
Prove that using 4 weightings, the fake coin can be found in 14 but not in 15 coins.