There are 5 locks and corresponding 5 keys, now use 5 keys to open 5 locks, let the keys correspond to the locks one by one, how many times do you have to try at most?
有5把锁和对应的5把钥匙，现在用5把钥匙去打开5把锁，让钥匙和锁一一对应，最多要试多少次．
<gadget id="calculator">4 + 3 + 2 + 1</gadget>
<output>10</output>

<result>10</result>