The school runway is 50 meters long, and a flag is inserted every 5 meters on one side, and the two ends are not inserted, how many flags are needed.
学校跑道长50米，在一侧每隔5米插一面旗，两端不插，需要多少面旗．
<gadget id="calculator">50 / 5</gadget>
<output>10</output>

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

<result>9</result>