From the natural numbers 1, 2, 3, 4, ..., 1996, how many numbers can be taken at most so that the difference between every two numbers taken out is not equal to 4.
从1，2，3，4，…，1996这些自然数中，最多可以取出多少个数来，才能使取出的每两个数的差不等于4．
<gadget id="calculator">1_996 / 4</gadget>
<output>499</output>

<gadget id="calculator">499 - 1</gadget>
<output>498</output>

<gadget id="calculator">498 / 2</gadget>
<output>249</output>

<gadget id="calculator">249 + 1</gadget>
<output>250</output>

<gadget id="calculator">250 * 4</gadget>
<output>1_000</output>

<result>1_000</result>