Determine the type of triangle (acute, obtuse, or right-angled) based on its side lengths.

Three natural numbers are given – the sides of a triangle.

Output one of the following words: right for a right-angled triangle, acute for an acute triangle, obtuse for an obtuse triangle, or impossible if the inputs don’t form a triangle.

[{'input': '3\n4\n5', 'output': 'right'}]