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.*;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner((System.in));
        int n = scanner.nextInt();
        List<Integer> list = new ArrayList<>();
        for(int i=0;i<n;i++){
            list.add(scanner.nextInt());
        }
        ArrayList<String> strings = new ArrayList<>();
        while (true){
            if(list.size()==1){
                break;
            }
            function(list,strings);
        }
        System.out.println(list.get(0));
        for (String string : strings) {
            System.out.println(string);
        }
    }
    static void function(List<Integer> list,List<String> strings){
        Collections.sort(list);
        int temp;
        if(list.size()==2){
            temp = list.get(1) - list.get(0);

        }else {
             temp = list.get(0) - list.get(1);
        }
        strings.add(list.get(0)+" "+list.get(1));
        list.remove(1);
        list.remove(0);
        list.add(0,temp);
    }
}