Install telephone poles on one side of a 500-meter-long road, and erect one pole every 50 meters. If no two ends of the road are erected, how many telephone 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>