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
/*
......................................................................................................................................
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....................................................................................:.................................................
......................................................................................................................................
......................................................................................................................................
 */


import javax.swing.text.DateFormatter;
import java.io.IOException;
import java.io.InputStream;
import java.math.BigInteger;
import java.time.DateTimeException;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.util.*;
import java.util.List;
import java.util.function.*;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;

import static java.lang.Math.max;
import static java.lang.Math.min;
import static java.lang.Math.pow;
import static java.lang.Math.abs;

import static java.lang.String.format;


public class Main {
    final static int INF = Integer.MAX_VALUE>>1;
    final static int MOD = 1_000_000_007;
    final static int[] dx4 = { 0, 1, 0, -1 };
    final static int[] dy4 = { 1, 0, -1, 0 };
    final static int[] dx8 = {0, 1, 1,  1,  0, -1, -1, -1};
    final static int[] dy8 = {1, 1, 0, -1, -1, -1, 0, 1};
    public static void main(String[] args) {
        Scanner sc=new Scanner();
        int n = sc.nextInt();
        List<FixedIntPair> list = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            list.add(new FixedIntPair(i,sc.nextInt()));
        }

        List<FixedIntPair> list2=new ArrayList<>(list);

        list2.sort(Comparator.comparing(fip->fip.y));
        long ans=0;
        List<FixedIntPair> pList = new ArrayList<>();
        List<FixedIntPair> mList = new ArrayList<>();
        if(list2.get(0).y>=0){
            ans-=list2.get(0).y;
            mList.add(list2.get(0));
            for (int i = 1; i < n; i++) {
                ans+=list2.get(i).y;
                pList.add(list2.get(i));
            }
        }else if(list2.get(list2.size()-1).y<=0){
            for (int i = 0; i < n - 1; i++) {
                ans-=list2.get(i).y;
                mList.add(list2.get(i));
            }
            ans += list2.get(list2.size() - 1).y;
            pList.add(list2.get(list2.size()-1));
        }else{
            for (int i = 0; i < n; i++) {
                if(list2.get(i).y>0){
                    pList.add(list2.get(i));
                }else{
                    mList.add(list2.get(i));
                }
                ans+=abs(list2.get(i).y);
            }
        }
        StringBuilder sb=new StringBuilder();
        sb.append(ans+"\n");

        List<FixedIntPair> ansList=new ArrayList<>();

        if(pList.size()>1&&mList.size()>1){

            ansList.add(new FixedIntPair(pList.remove(0).y,mList.remove(0).y));
            while(mList.size()>1){
                ansList.add(new FixedIntPair(ansList.get(ansList.size()-1).x-ansList.get(ansList.size()-1).y,mList.remove(0).y));
            }
            int x=ansList.get(ansList.size()-1).x-ansList.get(ansList.size()-1).y;
            int mCnt=0;
            while(pList.size()>0){
                if(mCnt==0){
                    ansList.add(new FixedIntPair(mList.remove(0).y,pList.remove(0).y));
                }else{
                    ansList.add(new FixedIntPair(ansList.get(ansList.size()-1).x-ansList.get(ansList.size()-1).y,pList.remove(0).y));
                }
                mCnt++;
            }
            int y=ansList.get(ansList.size()-1).x-ansList.get(ansList.size()-1).y;
            ansList.add(new FixedIntPair(x,y));
        }else if(pList.size()==1){
            ansList.add(new FixedIntPair(pList.remove(0).y,mList.remove(0).y));
            while(mList.size()>0){
                ansList.add(new FixedIntPair(ansList.get(ansList.size()-1).x-ansList.get(ansList.size()-1).y,mList.remove(0).y));
            }
        }else{
            ansList.add(new FixedIntPair(mList.remove(0).y,pList.remove(0).y));
            while(pList.size()>1){
                ansList.add(new FixedIntPair(ansList.get(ansList.size()-1).x-ansList.get(ansList.size()-1).y,pList.remove(0).y));
            }
            ansList.add(new FixedIntPair(pList.remove(0).y,ansList.get(ansList.size()-1).x-ansList.get(ansList.size()-1).y));
        }

        for(FixedIntPair fip:ansList){
            sb.append(fip.x);
            sb.append(" ");
            sb.append(fip.y);
            sb.append("\n");
        }
        put(sb);


    }


    public static void print(Object object){
        System.out.print(object);
    }
    public static void put(Object object) {
        System.out.println(object);
    }
    public static void put(){
        System.out.println();
    }

    public static void printE(Object object){
        System.err.print("DEBUG:"+object);
    }
    public static void putE(Object object){
        System.err.println("DEBUG:"+object);
    }
    public static void putE(){
        System.err.println("DEBUG:");
    }

    public static void print(String format,Object... args){
        System.out.print(String.format(format,args));
    }
    public static void put(String format,Object... args) {
        System.out.println(String.format(format,args));
    }
    public static void printE(String format,Object... args){
        System.err.print("DEBUG:"+String.format(format,args));
    }
    public static void putE(String format,Object... args){
        System.err.println("DEBUG:"+String.format(format,args));
    }

    final static private class Scanner {
        private final InputStream in = System.in;
        private final byte[] buffer = new byte[1024];
        private int ptr = 0;
        private int buflen = 0;

        private boolean hasNextByte() {
            if (ptr < buflen) {
                return true;
            } else {
                ptr = 0;
                try {
                    buflen = in.read(buffer);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (buflen <= 0) {
                    return false;
                }
            }
            return true;
        }

        private int readByte() {
            if (hasNextByte())
                return buffer[ptr++];
            else
                return -1;
        }

        private boolean isPrintableChar(int c) {
            return 33 <= c && c <= 126;
        }

        public boolean hasNext() {
            while (hasNextByte() && !isPrintableChar(buffer[ptr]))
                ptr++;
            return hasNextByte();
        }

        public String next() {
            if (!hasNext())
                throw new NoSuchElementException();
            StringBuilder sb = new StringBuilder();
            int b = readByte();
            while (isPrintableChar(b)) {
                sb.appendCodePoint(b);
                b = readByte();
            }
            return sb.toString();
        }

        public long nextLong() {
            if (!hasNext())
                throw new NoSuchElementException();
            long n = 0;
            boolean minus = false;
            int b = readByte();
            if (b == '-') {
                minus = true;
                b = readByte();
            }
            if (b < '0' || '9' < b) {
                throw new NumberFormatException();
            }
            while (true) {
                if ('0' <= b && b <= '9') {
                    n *= 10;
                    n += b - '0';
                } else if (b == -1 || !isPrintableChar(b)) {
                    return minus ? -n : n;
                } else {
                    throw new NumberFormatException();
                }
                b = readByte();
            }
        }

        public int nextInt() {
            long nl = nextLong();
            if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
                throw new NumberFormatException();
            return (int) nl;
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }
    }
    final static private class FixedIntPair {
        final public int x, y;
        final static public FixedIntPair ZEROS=new FixedIntPair(0,0);
        FixedIntPair(int x, int y) {
            this.x = x;
            this.y = y;
        }
        public static double distance(FixedIntPair fip1,FixedIntPair fip2){
            double x = (double) fip1.x - fip2.x;
            double y = (double) fip1.y - fip2.y;
            return Math.sqrt(x*x+y*y);
        }

        @Override
        public int hashCode() {
            return x+y;
        }

        @Override
        public boolean equals(Object obj) {
            if(obj==null)return false;
            if(!(obj instanceof FixedIntPair)) return false;
            FixedIntPair pair=(FixedIntPair) obj;
            return this.x==pair.x&&this.y==pair.y;
        }

        @Override
        public String toString() {
            return String.format(FixedIntPair.class.getSimpleName()+":(%d,%d)", x, y);
        }
    }
    final static private class FixedLongPair {
        final public long x, y;
        final static public FixedLongPair ZEROS=new FixedLongPair(0,0);
        FixedLongPair(long x, long y) {
            this.x = x;
            this.y = y;
        }
        public static double distance(FixedLongPair flp1,FixedLongPair flp2){
            double x = (double) flp1.x - flp2.x;
            double y = (double) flp1.y - flp2.y;
            return Math.sqrt(x*x+y*y);
        }

        @Override
        public int hashCode() {
            return (int)x+(int)y;
        }

        @Override
        public boolean equals(Object obj) {
            if(obj==null)return false;
            if(!(obj instanceof FixedLongPair)) return false;
            FixedLongPair pair=(FixedLongPair)obj;
            return this.x==pair.x&&this.y==pair.y;
        }

        @Override
        public String toString() {
            return String.format(FixedLongPair.class.getSimpleName()+":(%d,%d)", x, y);
        }
    }
    final static private class Binary{
        public static String toZeroPadding(int i){
            return String.format("%"+Integer.toBinaryString(-1).length()+"s",Integer.toBinaryString(i)).replace(' ','0');
        }
        public static String toZeroPadding(long i){
            return String.format("%"+Long.toBinaryString(-1).length()+"s",Long.toBinaryString(i)).replace(' ','0');
        }
    }

    final static private class Util {
        static long gcd(long a,long b){
            a=Math.abs(a);
            b=Math.abs(b);
            if(a<b){
                long tmp=a;
                a=b;
                b=tmp;
            }
            while(b!=0){
                long r=a%b;
                a=b;
                b=r;
            }
            return a;
        }
        static int gcd(int a,int b){
            a=Math.abs(a);
            b=Math.abs(b);
            if(a<b){
                int tmp=a;
                a=b;
                b=tmp;
            }
            while(b!=0){
                int r=a%b;
                a=b;
                b=r;
            }
            return a;
        }
        static long lcm(long a,long b){
            long gcd=gcd(a,b);
            long result=b/gcd;
            return a*result;
        }
        static boolean isValidCell(int i,int j,int h,int w){
            return i>=0&&i<h&&j>=0&&j<w;
        }
    }
}
