Stats in a java program

Stats.java

public class Stats

{

    public static void main(String[] args)

{

        int N = Integer.parseInt(args[0]);

        double[] a = new double[N];

        for (int i = 0; i < N; i++)

       {

            a[i] = StdIn.readDouble();

        }

        double sum = 0.0;

        for (int i = 0; i < N; i++)

        {

            sum += a[i];

        }

        double mean = sum / N;

         double sum2 = 0.0;

        for (int i = 0; i < N; i++)

        {

            sum2 += (a[i] - mean) * (a[i] - mean);

        }

        double stddev = Math.sqrt(sum2) / (N - 1);

        StdOut.println("Mean               = " + mean);

        StdOut.println("Standard deviation = " + stddev);

    }

}