During mine blasting, in order to ensure safety, after igniting the fuse, move to a safe area 400m away before blasting. The burning speed of the lead-in wire is 1 m/s, and the speed of people leaving is 5 m/s, how many meters is the minimum required for the fuse.
矿山爆破时，为确保安全，点燃引火线后，要在爆破前转移到400m以外的安全地区．引入线燃烧速度为1米/秒，人离开的速度是5米/秒，导火线至少需要多少米．
<gadget id="calculator">400 / 5</gadget>
<output>80</output>

<gadget id="calculator">80 * 1</gadget>
<output>80</output>

<result>80</result>