The property manager has 5 keys and 5 locks, one of which is matched with a lock, the naughty Big Big Wolf messed them up while the manager was sleeping, and how many times would it take to re-pair them.
物业管理员有5把钥匙和5把锁，其中一把钥匙配一把锁，调皮的灰太狼趁管理员睡觉的时候将它们搞乱了，要把它们重新配对，最多要试多少次．
<gadget id="calculator">4 + 3 + 2 + 1</gadget>
<output>10</output>

<result>10</result>