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: Zoe:  How did you pilot the rocket , Doctor ?
Dr. Who: I do n't think we 've met have we ?
Dr. Gemma Corwyn: Zoe ... Doctor ... John Smith , is n't it ?
Jamie: John ... John ...
Dr. Who: John ... John ...
Zoe: I 'm an astrophysicist . Pure - mathematics major .
Dr. Gemma Corwyn: With honors .
Dr. Who: Oh , I am impressed .
Dr. Gemma Corwyn: We use Zoe as our second opinion .
Zoe: You did n't answer my question .
Dr. Who: What question ?
Jamie: You know , I surprised you did n't know the answer . Now , do n't tell me there is something you ca n't work out !
Zoe: How did you pilot the rocket ship ? You see , I 've calculated its original course . It was a surface and supply station for Number Five Station , overdue and presumed lost nine weeks ago . Well the rocket could n't have drifted eighty seven million miles off course .
Dr. Who: So what 's your theory ?
Zoe: Well , there is a record of the last contract with the Silver Carrier rocket . It had seven million miles to touchdown , and enough fuel for twenty million . Well , it could n't have drifted here off course in the time involved . It must have been driven and piloted .
Jamie: Och , you are a right wee space - detective !
Zoe: There 's only one solution . That rocket was re - fuelled in space . - Provided for at least with another twelve fuel rods .
Dr. Who: Well , it is an interesting theory ...
Zoe: Oh , it is n't a theory . You ca n't disprove the facts . It 's pure logic .
Dr. Who: Logic , my dear Zoe , merely enables one to be wrong with authority . Supposing there was a faulty automatic pilot ?
Zoe: To drive a rocket eighty seven million miles on fuel for _ twenty _ million ?
Dr. Who: Well , it 's a possibility .
Zoe: That rocket was driven here somehow . I know it was .

miles