A storybook has 500 pages. Xiaohua reads 140 pages on the first day and 294 pages on the second day. Which page should she start reading on the third day?
一本故事书500页，小华第一天看了140页，第二天看了294页，她第三天应从第几页看起？
<gadget id="calculator">140 + 294 + 1</gadget>
<output>435</output>

<result>435</result>