// Sum2.java

class SumThread extends Thread {
    private int from, to, sum;
    
    public SumThread(int from, int to) {
        this.from = from;
        this.to = to;
        sum = 0;
    }

    @Override
    public void run() {
        for (int i = from; i <= to; i++) {
            sum += i;
        } 
    }

    public int getSum() {
        return sum;
    }
}


public class Sum2 {
    public static void main(String args[]) {
        SumThread t1 = new SumThread(1, 5000);
        SumThread t2 = new SumThread(5001, 10000);
        t1.start();
        t2.start();

        // wait for the threads to finish!
        try {
            t1.join();
            t2.join();
        } catch (InterruptedException e) {
            System.out.println("Interrupted");
        }

        System.out.printf("The sum of 1-1000 is %d.\n", t1.getSum() + t2.getSum());
    }
}