public class Pi{    public static void main(String args[])    {        double pi = 0;           for (int i = 1; i <= 1000; i++)        {            pi += Math.pow(-1, i+1) * 4 / (i * 2 -1);            System.out.println(" " + i + "             " + pi);           }        System.exit(0);       }   }