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.
Q: Doctor Bashir: Nervous , Chief ?
Chief O'Brien: What 're you talking about ?
Doctor Bashir: That 's your fifth cup of coffee in twenty minutes .
Chief O'Brien: I did n't realize you were keeping track .
Doctor Bashir: Oh , nervous and irascible .
Chief O'Brien: If you had n't seen your wife and child for two months , you 'd be irascible too .
Doctor Bashir: Well , believe me , I 'm looking forward to Keiko and Molly 's visit as much as you are .
Chief O'Brien: Ha - ha , I doubt that .
Doctor Bashir: How many games of raquetball have we played in the last two months ?
Chief O'Brien: I do n't know , um ... Fifteen , maybe twenty ?
Doctor Bashir: No , try _ seventy _ . I 've been keeping track of that , too . And you know what all those games have proved to me ? That I 'm a poor substitute for your wife .
Chief O'Brien: I could 've told you that sixty games ago .
A:
games