There are 100 children, and each of them has a number on their chest. The number varies from 1 to 100. Please select a number of children and arrange them in a circle so that the product of the numbers of any two adjacent children is less than 100. Then How many children can you choose at most?
有100个小孩，每人胸前有一个号码，号码从1到100各不相同，请你挑选出若干个小孩，排成一个圆圈，使任何相邻两个小孩的号码的乘积小于100，那么你最多能挑选出多少个小孩．
<result>18</result>