There is a 60-meter long corridor in the school. It is planned to put potted flowers every 3 meters. If the two ends are not placed, how many potted flowers can be placed?
学校有一条60米的长廊，计划每隔3米放一盆花，如果两端不放，能放几盆花？
<gadget id="calculator">60 / 3</gadget>
<output>20</output>

<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<result>19</result>