0 a device such as a bell or siren that warns the people in a building that the building is on fire:
1 a device that makes a loud continuous noise to warn people to leave a burning building
2 a piece of equipment that makes a loud noise to warn people of a fire in a building, or a switch connected to this equipment:
An electrical fault had set off the fire alarm.
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.