Among the 2002 numbers of 1, 2, 3, ..., 1999, 2000, 2001, 2002, how many numbers can be selected at most, so that the sum of any 3 numbers among the selected numbers is a multiple of 3.
在1，2，3，…，1999，2000，2001，2002这2002个数中，至多能选出多少个数，使得所选出的数中，任意3个数的和都是3的倍数．
<gadget id="calculator">2_001 / 3</gadget>
<output>667</output>

<gadget id="calculator">667 + 1</gadget>
<output>668</output>

<result>668</result>