A key can only open one lock. Now there are 5 keys and 4 locks, but they are all messed up. How many times can you find the corresponding key for each lock?
一把钥匙只开一把锁，现在有5把钥匙和4把锁，但它们全部都搞乱了，最多需要多少次才能为每把锁找到相应的钥匙．
<gadget id="calculator">4 + 3 + 2 + 1</gadget>
<output>10</output>

<result>10</result>