In this task, you're given an open-domain question. Your task is to provide an answer to the given question. There is only one unique answer for each question. Your answer should be short, and refer to an entity, date, number, etc. Do not put your answer in the context of a sentence.

How many miles is the mexican border to the united states?
1,954 mi

Who painted sunday afternoon on the island of la grande jatte?
Georges-Pierre Seurat

When was the first airplane used in war?

Nieuport IV