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 PyPy3 (2.4.0) (judge verdict: Accepted)

import sys
#import numpy as np
import math
#from fractions import Fraction
#import itertools
#from collections import deque
#import heapq
#from fractions  import gcd
#input=sys.stdin.readline
n=int(input())
a=list(map(int,input().split()))
M=max(a)
m=min(a)
resm=m
resM=M
c_M=False
c_m=False
ans=[]
for i in range(n):
    if a[i]==M and c_M==False:
        c_M=True
        continue
    elif a[i]==m and c_m==False:
        c_m=True
        continue
    if a[i]>0:
        ans.append((resm,a[i]))
        resm=resm-a[i]
    else:
        ans.append((resM,a[i]))
        resM=resM-a[i]
print(resM-resm)
for i in ans:
    print(*i)
print(resM,resm)