From the fifty numbers of 1, 2, 3, ..., 50, take out a number of numbers so that the sum of any two of them cannot be divisible by 7, then how many numbers can be taken out at most.
从1、2、3、…、50这五十个数中，取出若干个数，使其中任意两个数的和都不能被7整除，则最多能取出多少个数．
<gadget id="calculator">7 * 2</gadget>
<output>14</output>

<gadget id="calculator">8 + 14 + 1</gadget>
<output>23</output>

<result>23</result>