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}

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}

Examples

Input

3
1 -1 2


Output

4
-1 1
2 -2


Input

3
1 1 1


Output

1
1 1
1 0
import java.util.*;
import java.io.*;
import java.nio.charset.StandardCharsets;

public class Main {
	int N;
	long[] A;
	Deque<Long> queue;
	List<String> logs;

	Main(int N, long[] A) {
		this.N = N;
		this.A = A;
		this.queue = new ArrayDeque<>();
		Arrays.sort(A);
		for (int i = 0; i < N; ++i) {
			queue.add(A[i]);
		}
		this.logs = new ArrayList<>();

		calc();
		show();
	}

	void calc() {
		while (queue.size() > 2) {
			long first = queue.pollFirst();
			long last = queue.pollLast();
			long diffA = Math.abs(queue.peekFirst() - (first - last));
			long diffB = Math.abs(queue.peekLast() - (last - first));
			if (diffA >= diffB) {
				queue.addFirst(first - last);
				this.logs.add(first + " " + last);
			} else {
				queue.add(last - first);
				this.logs.add(last + " " + first);
			}
		}
		long s = queue.poll();
		long f = queue.poll();
		queue.add(f - s);
		this.logs.add(f + " " + s);

	}

	void show() {
		System.out.println(queue.poll());
		for (int i = 0; i < this.logs.size(); ++i) {
			System.out.println(this.logs.get(i));
		}
	}

	public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		int N = Integer.parseInt(in.readLine());
		long[] A = new long[N];
		String[] tokens = in.readLine().split(" ");

		in.close();
		for (int i = 0; i < N; ++i) {
			A[i] = Long.parseLong(tokens[i]);
		}

		Main ins = new Main(N, A);

	}

}