The ticket price of Century Park is: 5 yuan per person; if you buy more than 30 tickets at one time, you will be charged 1 yuan less for each ticket. I would like to ask: When the number of people is less than 30, at least how many people must go to Century Park, and it is more cost-effective to buy 30 tickets.
世纪公园的票价是：每人5元；一次购票满30张，每张票就少收1元．请问：当人数少于30人时，至少要有多少人去世纪公园，买30张票反而合算．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">30 * 4</gadget>
<output>120</output>

<gadget id="calculator">120 / 5</gadget>
<output>24</output>

<gadget id="calculator">24 + 1</gadget>
<output>25</output>

<result>25</result>