import javax.swing.*;

public class Goldbachs {

    // This method decides if number is prime or not and returns true or false.
    public static boolean isPrime(int i) {
        for (int u = 2; u < i; u++) {
            if (i%u==0)
                return false;
        }
        return true;
    }

    public static void main (String[] args) {

        while (true) {
            String s = JOptionPane.showInputDialog("Insert an even number greater "
                + "than 2 and I'll calculate \nwhich primes can be summed up"
                    + " to form that number!", JOptionPane.QUESTION_MESSAGE);
            if (s == null)
                break;

            int inputNumber = Integer.parseInt(s);
            String result = "";
            int numberofRows = 0;

            //Does inputNumber meet the requirements?
            if (inputNumber>2 && inputNumber%2==0) {
            //Which prime numbers are canditates to form inputNumber?
                for (int p = 1; p <=(inputNumber/2); p++) {
                //Is there another prime suitable to form inputNumber?
                    if ((isPrime(p)) && (isPrime(inputNumber-p))) {
                        result = result + p + " + " + (inputNumber-p) + "\n";
                            numberofRows = numberofRows + 1;
                        }
                    }
            if (numberofRows > 30) {
                System.out.println (result);
            }
            else {
                JOptionPane.showMessageDialog(null, result , "Here are your primes!",
                    JOptionPane.INFORMATION_MESSAGE);
            }
            }

            else {
                JOptionPane.showMessageDialog(null, "Invalid number, please pick a"
                + " new one.", "Number does not meet the requirements!", JOptionPane.ERROR_MESSAGE);
            }
        }
    }
}