If a natural number plus 10 or minus 10 is a perfect square number, what is the natural number?
某自然数加10或减10，都是完全平方数，则这个自然数是多少．
<gadget id="calculator">6 ** 2</gadget>
<output>36</output>

<gadget id="calculator">36 - 10</gadget>
<output>26</output>

<result>26</result>