Simple, take the first minus staff and use it at the tiny mushroom, this will lift you up,
then mauveur to the hill below you to find another minus staff, then go to the far right
mushroom and shrink it, look above and get the third minus staff then head to the second
area.

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Now head to the right as far as you can go and use the minus staff on the vines in the
boulder, this will open a path, go down it and collect the other minus staff, then head up
to the boulder that was on the other side of the stream and use the minus staff on it,
this will knock two minus staffs out of a tree, now head over to the first boulder and
realese it from the vines, thus blocking the stream completly, then head over to the bush
below it and shrink it, then head down to the bottom og the former stream and collect the
last minus staff, head up to the broken bridge, don't repair it! , and shrink the bush
next to it, and you will find your way out.

Hope this helps, i'm still trying to figure out how to get the box there though. -_-