A bridge is 3,600 meters long. When a train crosses the bridge, each branch is 800 meters long. It takes 5 minutes from the time the train gets on the bridge to when the train leaves the bridge. How long is the train?
一座大桥长3600米，一列火车通过大桥时每分行800米，从车头开上桥到车尾离开桥共用5分钟，火车长多少米？
<gadget id="calculator">5 * 800</gadget>
<output>4_000</output>

<gadget id="calculator">4_000 - 3_600</gadget>
<output>400</output>

<result>400</result>