public class JavaApplication1 {
  public static void main(String[] args) {
    System.out.println("Hello World!");
    Calculator calc = new Calculator();
    System.out.println("2+2=" + calc.sum(2, 2));
  }

  public static class Adder {

    private int sum;
    public Adder() { sum = 0; }
    public Adder(int a) { this.sum = a; }
    
    public void add (int b) {
      sum += b;
    }

    public int getSum() { return sum; }

  }

  public static class Calculator {
    public int sum(int... a) {
      Adder adder = new Adder();
      for (int i:a) {
        adder.add(i);
      }
      return adder.getSum();
    }
  }
};