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: Accepted)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) throws IOException {
		Main mainObj = new Main();
		mainObj.solve();
	}

	public void solve() throws IOException {
		FastScanner fs = new FastScanner();
		int n = fs.nextInt();
		int[] aArr = fs.nextIntArr(n);
		Arrays.sort(aArr);
//		System.out.println(Arrays.toString(aArr));
		
		ArrayList<String> tejunList = new ArrayList<>();
		
		long ans = 0;
		
		// 全部負の数
		if(aArr[aArr.length - 1] < 0) {
			long leftVal = aArr[n-1];
			for(int i =0; i < aArr.length - 1; i++) {
				tejunList.add(leftVal+" "+aArr[i]);
//				System.out.print(leftVal);
//				System.out.print(" ");
//				System.out.print(aArr[i]);
//				System.out.print("\n");
				leftVal -= aArr[i];
			}
			ans = leftVal;
		// 全部正の場合
		}else if(aArr[0] >= 0) {
			long leftVal = aArr[0];
			for(int i =1; i < aArr.length - 1; i++) {
				tejunList.add(leftVal+" "+aArr[i]);
//				System.out.print(leftVal);
//				System.out.print(" ");
//				System.out.print(aArr[i]);
//				System.out.print("\n");
				leftVal -= aArr[i];
			}
			tejunList.add(aArr[n-1]+" "+leftVal);
//			System.out.print(aArr[n-1]);
//			System.out.print(" ");
//			System.out.print(leftVal);
//			System.out.print("\n");
			
			ans = aArr[n-1] - leftVal;
		// 負と正が混じっている場合
		}else {
			int index = 1;
			while(aArr[index] < 0) {
				tejunList.add(aArr[n-1]+" "+aArr[index]);
//				System.out.print(aArr[n-1]);
//				System.out.print(" ");
//				System.out.print(aArr[index]);
//				System.out.print("\n");
				aArr[n-1] -= aArr[index];
				index++;
			}
			for(int i = index;i < n-1; i++) {
				tejunList.add(aArr[0]+" "+aArr[i]);
//				System.out.print(aArr[0]);
//				System.out.print(" ");
//				System.out.print(aArr[i]);
//				System.out.print("\n");
				aArr[0] -= aArr[i];
			}
			tejunList.add(aArr[n-1]+ " "+ aArr[0]);
//			System.out.print(aArr[n-1]);
//			System.out.print(" ");
//			System.out.print(aArr[0]);
//			System.out.print("\n");
			ans = aArr[n-1] - aArr[0];
		}
		
		System.out.println(ans);
		for(String str : tejunList) {
			System.out.println(str);
		}
	}

	

	public class FastScanner {

		BufferedReader reader;
		private StringTokenizer st;

		public FastScanner() {
			st = null;
			reader = new BufferedReader(new InputStreamReader(System.in));
		}

		public String next() throws IOException {
			if (st == null || !st.hasMoreElements()) {
				st = new StringTokenizer(reader.readLine());
			}
			return st.nextToken();
		}

		public String nextLine() throws IOException {
			st = null;
			String readLine = null;
			readLine = reader.readLine();
			return readLine;
		}

		public int nextInt() throws NumberFormatException, IOException {
			return Integer.parseInt(next());
		}

		public long nextLong() throws NumberFormatException, IOException {
			return Long.parseLong(next());
		}

		public int[] nextIntArr(int n) throws NumberFormatException, IOException {
			int[] retArr = new int[n];
			for (int i = 0; i < n; i++) {
				retArr[i] = nextInt();
			}
			return retArr;
		}

		public long[] nextLongArr(int n) throws NumberFormatException, IOException {
			long[] retArr = new long[n];
			for (int i = 0; i < n; i++) {
				retArr[i] = nextLong();
			}
			return retArr;
		}

		public void close() throws IOException {
			reader.close();
		}
	}

}