#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Triangle Project Code.


# triangle(a, b, c) analyzes the lengths of the sides of a triangle
# (represented by a, b and c) and returns the type of triangle.
#
# It returns:
#   'equilateral'  if all sides are equal
#   'isosceles'    if exactly 2 sides are equal
#   'scalene'      if no sides are equal
#
# The tests for this method can be found in
#   about_triangle_project.py
# and
#   about_triangle_project_2.py
#
def triangle(a, b, c):

	if (a<=0 or b<=0 or c<=0):
		raise TriangleError
	if (a+b<=c or b+c<=a or c+a<=b):
		raise TriangleError	

	n = 0
	if a==b: n+=1
	if b==c: n+=1
	if c==a: n+=1

	if n>1: return 'equilateral'
	elif n == 1: return 'isosceles'
	else: return 'scalene'

# Error class used in part 2.  No need to change this code.
class TriangleError(StandardError):
    pass
