A set of books is numbered from 1, 2, 3, and 4, and a total of 324 characters are used. How many pages are there in this set of books?
一套书从1，2，3，4开始编页，一共用了324个字，这套书共有多少页？
<gadget id="calculator">145 - 1</gadget>
<output>144</output>

<result>144</result>