# Plain Sum

### Instructions

Write a function `int plainSum(int, int, int)` which takes 3 integers and returns their sum.

Functions in Dart are declared as follows:

```dart
bool isEven(int num) {
  return num % 2;
}
```

### Usage

```dart
void main() {
  var res = plainSum(1, 2, 3);
  print(res); // prints 6
}
```