There are 49 children, and each of them has a number on their chest. The numbers vary from 1 to 49. Please pick out several children and arrange them in a circle so that the product of the numbers of any two adjacent children is less than 100 , how many children can you pick out at most?
有49个小孩子，每人胸前有一个号码，号码从1到49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数的乘积小于100，你最多能挑选出多少个小孩子？
<result>18</result>