On pokemon mystery dungeon blue rescue team how do you get chestnuts...?

where do you get chestnuts and how do you get them for the mankey gang

On pokemon mystery dungeon blue rescue team how do you get chestnuts...?
here's a little piece from my guide book page 87 so READ CAREFULLY then do so

UPROAR FOREST-%26gt; DON'T forget the very valuable chestnuts you find on B9F these are neede 2 complete the renovation of your base. so be sure 2 pick up some while you are here; you can always go back for more chestnuts also this is the first dungeon that A MONSTER HOUSES may appear in (stay alert on that they drop in on you when u least expect it so if u have any petrify orbs in storage bring them) so just have room in your bag 4 chestnuts. glad 2 help :)

if u have questions let me know i have the red version %26amp; the guide book.