triangle1 – Three Triangle Types (challenge)

Every triangle can be classified as either scalene, isosceles or equilateral:

equilateral triangles have all edges of the same size;
isosceles triangles have exactly two edges of the same size;
scanele triangles have three edges of different sizes.

(Some authors consider equilateral to be a special case of isosceles. For the purpose of this exercise, we use Euclid’s original definition and consider isosceles triangles those with exactly two edges of the same size.)

triangle types: scalene, isosceles, equilateral, impossible

Write a program that given three edge sizes determines whether a triangle is scalene, isosceles, equilateral or impossible.

Input and Output

The input consists of a single line with three natural numbers x, y and z where 0 < x, y, z < 100

The output should contain a single line with just scalene, isosceles, equilateral or impossible.

Example input 1

3 4 5

Example output 1

scalene

Example input 2

3 3 1

Example output 2

isosceles

Example input 3

6 2 3

Example output 3

impossible

Example input 4

4 4 4

Example output 4

equilateral

Scoring

4/12: works for the above examples
12/12: works for other test cases

try first: good1 signum1

try next: factorial1

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