喝汽水，1瓶汽水1元，2个空瓶可以换一瓶汽水，给20元，可以多少汽水。编程实现。

#include <stdio.h>
#include <assert.h>

int drink_water(unsigned int money)
{
int bot = money;
int empty = money;
while(empty > 1)
{
bot +=empty/2;
empty=empty/2+empty%2;
}
return bot;
}

int main()
{
unsigned int money;
int bottles;
scanf("%u",&money);
bottles = drink_water(money);
printf("you can drink %d bottles of water\n",bottles);
return 0;
}