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: Leonard Hofstadter:  Let me ask you something : do you think it 's okay for Penny to have an ex - boyfriend sleep on her couch ?
Howard Wolowitz: No , I mean she 's obviously way out of line ...
Leonard Hofstadter: Thank you .
Howard Wolowitz: But if she dumps you , she 'll have a new boyfriend by tomorrow morning , and you 'll have a new girlfriend when you figure out how to build _ one _ .

girlfriend