class Sum {
	private int sum;
	
	public int getSum() { 
		return sum;
	}
	public void setSum(int sum) { 
		this.sum = sum;
	} 
}
class Summation implements Runnable {

	private int upper;
	private Sum sumValue;
	
	public Summation(int upper, Sum sumValue) {
		this.upper = upper;
		this.sumValue = sumValue;
	}
	public void run() {
		int sum = 0;
		for (int i = 0; i <= upper; i++)
			sum += i; 
		sumValue.setSum(sum);
	} 
	
	public static class Driver {
	
		public static void main(String[] args) {
			if (args.length > 0) {
				if (Integer.parseInt(args[0]) < 0)
					System.err.println(args[0] + " must be >= 0."); 
				else {
					// create the object to be shared
					Sum sumObject = new Sum();
					int upper = Integer.parseInt(args[0]);
					Thread thrd = new Thread(new Summation(upper, sumObject)); 
					thrd.start();
					try {
						thrd.join(); 
						System.out.println ("The sum of "+upper+" is "+sumObject.getSum()); 
					} 
					catch (InterruptedException ie) { 	
					}
				} 
			}
			else
				System.err.println("Usage: Summation <integer value>"); 
		}
	}
}