On the 800-meter roundabout, a colored flag was inserted every 50 meters. Later, some colored flags were added, and the interval between the colored flags was shortened. The colored flags at the starting point did not move. How many meters apart are the colored flags?
在800米环岛上，每隔50米插一面彩旗，后来又增加了一些彩旗，就把彩旗的间隔缩短了，起点的彩旗不动，重新插后发现，一共有四根彩旗没动，问现在的彩旗间隔多少米？
<gadget id="calculator">10 * 4</gadget>
<output>40</output>

<result>40</result>