Definition: In this task, you will use your knowledge about language (and common sense) to determine what element the marked number refers to. The numbers are marked with two underlines around them, like: _ number _. Your answer should be chosen from the given text, and should not contain other words.
Input: Brigadier Lethbridge Stewart:  A few months ago , the superpowers , Russia , America , and China , decided upon a plan to ensure peace . All three powers have hidden atomic missile sites . All _ three _ agreed to give details of those sites plus full operation instructions to another neutral country . In the event of trouble , that country could publish everyone 's secrets and so cool things down . Well , naturally enough the only country that could be trusted with such a role was Great Britain .
Doctor Who: Naturally , I mean the rest were all foreigners .
Brigadier Lethbridge Stewart: Exactly .

superpowers