Because two empty bottles for one bottle.

5/2=2 bottles ... and the remaining 1 empty bottles-bottles for wine.

After drinking, 2 empty bottles+1 empty bottle =3 empty bottles.

3/2= 1 bottle of wine ... The rest 1 bottle is empty-

After drinking, 1 empty bottle+remaining 1 empty bottle =2 empty bottles.

2/2= 1 bottle for spraying-

To sum up, drink 5+2+ 1+ 1=9 bottles of wine first.

Then you get 9 bottle caps, and the remaining 1 bottle is empty.

2/ Recalculate the cover page

Because a bottle of wine has four caps.

9/4=2 bottles .......................................................................................................................................................................

After drinking 2 empty bottles+1 before empty bottles +2 caps+1 caps, that is, 3 empty bottles and 3 caps.

At this time, there are less than four bottle caps left, so we can't change wine now.

Three bottles for one bottle

3/2= 1 bottle ... the remaining 1 empty bottle (there were 3 caps left before)-

Drink 1 bottle of new wine, empty bottle 1, lid 1.

Now add the remaining 1 empty bottles, and now there are 2 empty bottles.

Plus the previous three caps, there are now four caps.

2/2= 1 bottle)-

After a new sprinkling to quench thirst, 1 empty bottle and 1 lid are left.

Together with the previous four caps, there are now five caps, and the empty bottle is 1 bottle.

Five/change the wine cover

5/4= 1 bottle ... and the rest is 1 cap. - .

When the new wine is thirsty, empty bottles 1 and lids 1.

Then add the remaining bottles and caps, and now there are 2 empty bottles and 2 caps.

Six/change a bottle of wine

2/2= 1 bottle)-

After drinking the new bottle, empty bottle 1, cap 1, plus the remaining cap, empty bottle 1, cap 3.

No one can change the wine, so the wine change is over.

Eight/result: As the final result, you can drink 15 bottles of wine.