A bottle for experimentation, first put 1 cell, the number of cells doubles every minute, the whole bottle can be filled in 15 minutes, how many minutes will it take to fill half the bottle?
一个做实验的瓶子，先放入1个细胞，每分钟细胞个数增加1倍，15分钟可装满整瓶，问几分钟可充满半瓶？
<gadget id="calculator">15 - 1</gadget>
<output>14</output>

<result>14</result>