index
| submit
| rank
| book

## 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.)

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

index
| submit
| rank
| book

Copyright © 2020-2021 Rudy Matela