A square flower bed is surrounded by flower pots, and each side can hold 15 pots. How many pots of flowers can be placed around this flower bed at least.
一个正方形花坛的四周都摆上花盆，每边都能摆15盆，这个花坛四周最少可以摆多少盆花．
<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<gadget id="calculator">60 - 4</gadget>
<output>56</output>

<result>56</result>