import javax.swing.*;

public class Heron {

    public static void main (String[] args) {

        String input = JOptionPane.showInputDialog("Please enter a number");
        double x = Double.parseDouble(input);

        double a = 1;

        final double EPSILON = 0.0000001;

        while (Math.abs(a*a - x)/x > EPSILON) {
            a = (a + x/a) / 2;
        }

        JOptionPane.showMessageDialog(null,
                "The square root of " + input + " is " + a);

    }

}