A set of storybooks was published in year x for the first time, and then published every two years. The sum of the years of the first three publications is 5967. In what year was this set of stories published for the first time? (only list equations)
一套故事书第一次是在x年出版的，以后每过两年出版一次，前3次出版的年数和是5967，这套书第一次是在哪年出版的？(只列出方程)
<gadget id="calculator">5_967 - 2 - 2 - 2</gadget>
<output>5_961</output>

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

<gadget id="calculator">5_961 / 3</gadget>
<output>1_987</output>

<result>1_987</result>