Beibei was born on February 28, 2004, and Tiantian was born on March 3, 2004. How many days older is Beibei than Tiantian?
贝贝2004年2月28日出生，天天2004年3月3日出生，贝贝比天天大多少天．
<gadget id="calculator">29 - 28</gadget>
<output>1</output>

<gadget id="calculator">1 + 3</gadget>
<output>4</output>

<result>4</result>