If the difference between two four-digit numbers is 2013, we say that these two four-digit numbers are the "lucky number pairs" of this year. How many such "lucky number pairs" are there this year?
如果两个四位数的差是2013，我们就说这两个四位数是今年的"幸运数对"，那么今年这样的"幸运数对"共有多少对．
<gadget id="calculator">2_013 + 1_000</gadget>
<output>3_013</output>

<gadget id="calculator">9_999 - 3_013</gadget>
<output>6_986</output>

<gadget id="calculator">6_986 + 1</gadget>
<output>6_987</output>

<result>6_987</result>