There are 1 catty, 2 catties, 4 catties, 8 catties, and 16 catties of white sugar in one bag each, and the sugar is sold in whole bags. How many catties can customers buy?
现有1斤、2斤、4斤、8斤、16斤的白糖各一袋，白糖整袋卖，问顾客可买的斤数有多少种？
<gadget id="calculator">1 + 2 + 4 + 8 + 16</gadget>
<output>31</output>

<result>31</result>