## Max Num

### Instructions

Your task is to implement a function `maxNum`, which should accept three integer parameters and return the maximum of the three.

### Usage

```dart
void main() {
  print(maxNum(1, 2, 3));
  print(maxNum(0, 0, 0));
  print(maxNum(-1, -5, 0));
}
```

And its output :

```console
$ dart test.dart
3
0
0
$
```