A has a stamp and B has b stamp. If A gives B 10 stamps, they both have exactly the same number of stamps. How much difference are there between the two original stamps?
甲有a张邮票，乙有b张邮票．如果甲给乙10张，两人邮票张数正好同样多．两人原来的邮票相差多少张．
<gadget id="calculator">10 + 10</gadget>
<output>20</output>

<result>20</result>