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: Krillin:  The three of us here together reminds me of old times . Brings back a lot of fun memories . I remember we had a bet one time - we were suppposed to find a rock like this _ one _ with a turtle on its back and bring it back here . Oh , yeah ... and the loser had to go without dinner .
Adult Goku: That 's the worst way to lose for me .
Krillin: You and Master Roshi are the only people I know who haven't changed one bit in all the years that we 've been friends . I guess some people never get old . Unfortunately , I 'm not one of them .

rock