Xiao Ming wrote numbers according to certain rules: 1, +2, -3, 4, +5, -6, 7, +8, -9... When he finished writing 100 numbers, he stopped. Among the numbers he wrote, how many positive numbers are there in total?
小明按一定的规律写数字：1、+2、-3、4、+5、-6、7、+8、-9…，当他写完100个数时，他停了下来．在他所写的数中，一共有多少个正数．
<gadget id="calculator">99 / 3</gadget>
<output>33</output>

<gadget id="calculator">33 * 2</gadget>
<output>66</output>

<gadget id="calculator">66 + 1</gadget>
<output>67</output>

<result>67</result>