class Summation implements Runnable
{
    private int upper;
    private MutableInteger sumValue;
    public Summation (int upper, MutableInteger sumValue) {
	this.upper = upper;
	this.sumValue = sumValue;
    }
    public void run() {
	int sum = 0;
	for (int i = 0; i <= upper; i++)
	    sum += i;
	sumValue.setValue(sum);
    }
}