Write a series of numbers like this after 1993; each number is the difference between the two numbers before it (subtract the smaller from the larger one) such as after 1993, according to 9-3=6, then write 6; according to 6 -3=3, then write 3;...write it as 199363...follow this method and keep writing, what is the sum of the first 987 numbers in this string.
在1993的后面写一串这样的数字；每个数是它前面两个数的差(用较大的减去较小的)如1993后面，根据9-3=6，跟着写6；根据6-3=3，跟着写3；…写成199363…按这个方法一直写下去，这串数前987个数的和是多少．
<gadget id="calculator">1 + 9 + 9 + 3 + 6</gadget>
<output>28</output>

<gadget id="calculator">327 * 6</gadget>
<output>1_962</output>

<gadget id="calculator">28 + 1_962 + 3</gadget>
<output>1_993</output>

<result>1_993</result>