Problem:
Score : 500 points

Problem Statement

There are N integers, A_1, A_2, ..., A_N, written on a blackboard.

We will repeat the following operation N-1 times so that we have only one integer on the blackboard.

Choose two integers x and y on the blackboard and erase these two integers. Then, write a new integer x-y.

Find the maximum possible value of the final integer on the blackboard and a sequence of operations that maximizes the final integer.

Constraints

2 \leq N \leq 10^5

-10^4 \leq A_i \leq 10^4

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
A_1 A_2 ... A_N

Output

Print the maximum possible value M of the final integer on the blackboard, and a sequence of operations x_i, y_i that maximizes the final integer, in the format below.

Here x_i and y_i represent the integers x and y chosen in the i-th operation, respectively.

If there are multiple sequences of operations that maximize the final integer, any of them will be accepted.

M
x_1 y_1
:
x_{N-1} y_{N-1}

Sample Input 1

3
1 -1 2

Sample Output 1

4
-1 1
2 -2

If we choose x = -1 and y = 1 in the first operation, the set of integers written on the blackboard becomes (-2, 2).

Then, if we choose x = 2 and y = -2 in the second operation, the set of integers written on the blackboard becomes (4).

In this case, we have 4 as the final integer. We cannot end with a greater integer, so the answer is 4.

Sample Input 2

3
1 1 1

Sample Output 2

1
1 1
1 0

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        scanner.nextLine();

        ArrayList<Integer> integers = new ArrayList<>();
        ArrayList<Integer> results = new ArrayList<>();
        for(int i = 0; i < n; ++i) {
            integers.add(scanner.nextInt());
        }

//        for(Integer i : integers) {
//            System.out.println(i);
//        }


        for(int i = 1; i < n-1; ++ i) {
            Collections.sort(integers);
            int num1 = integers.get(0);
            int num2 = integers.get(1);
            integers.add(num1 - num2);
            results.add(num1);
            results.add(num2);
            integers.remove(0);
            integers.remove(0);
        }

        Collections.sort(integers);
        System.out.println(integers.get(1) - integers.get(0));
        results.add(integers.get(1));
        results.add(integers.get(0));

//        for(Integer i : integers) {
//            System.out.println(i);
//        }

        for(int i = 0; i < n; i += 2) {
            System.out.println(results.get(i) + " " + results.get(i+1));
        }
    }

}