There is a peculiar kind of caterpillar. A caterpillar grows to an adult and doubles in size every day. It can grow to 10 centimeters in 10 days, and how many days will it take to grow to 20 centimeters.
有一种奇特的毛毛虫，一条毛毛虫长到成虫，每天长一倍，10天能长到10厘米，长到20厘米时还要多少天．
<result>1</result>