haha,你没有炒过股票，这是被反向拆股的下场：

10 dollar = 5 beers;

5 beers = 5 bottles and 5 covers,

then recycle 4 bottles

      2 more beers, which means 2 more bottles and 2 more covers,

we now have 7 covers ,can recycle again, get 1 beers,  at hand, having

 3 + 1 covers, 1 + 2 bottles .

 

haha, recycle 4 covers, get a free beer first, then have 4 bottles, then can

change to 2 beers.

again, we can one more beer. But finanlly 3 covers left and one bottle left,

it 's time to go home.

5 +2 +1 +2 +1 = 11 ?

 

The trick is to recycle cover or bottle first ?