If one side of a road with a length of 500 meters is erected at intervals of 50 meters, if there are no poles at both ends of the road, how many poles are needed in total?
在一条长500米的公路一侧架设电线杆，每隔50米架设一根，若公路两端都不架设，共需电线杆多少根？
<gadget id="calculator">500 / 50</gadget>
<output>10</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<result>9</result>