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: Consider Input: Nathan:  So , do you know what the Turing Test is ?
Caleb: Yeah . I know what the Turing Test is . It 's when a human interacts with a computer and if the human does n't know they 're interacting with a computer , the test is passed .
Nathan: And what does a pass tell us ?
Caleb: That the computer has artificial intelligence . Are you building an AI ?
Nathan: I 've already built _ one _ .

Output: AI


Input: Consider Input: Ted Mosby:  Look , there 's a fine line between love and insanity . It 's the Dobler - Dahmer theory .
Lily Aldrin: Damn , I always forget the little _ one _ !
Ted Mosby: All right . If both people are into each other , a big romantic gesture works . Like Lloyd Dobler holding up the boom box outside Dianne Court 's window in Say Anything . But if one person is n't into the other , the same gesture comes off serial - killer crazy , or Dahmer .

Output: theory


Input: Consider Input: Green Goblin:  I 've been burning bridges all day , I think I 'll just knock this _ one _ down .


Output: bridges