Pages 5 and 16 of the evening newspaper are on the same side of the same sheet. How many sheets are there in this issue?
晚报的第5页和第16页在同一张的同一面，这期报纸共有多少张．
<gadget id="calculator">16 + 4</gadget>
<output>20</output>

<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<result>5</result>