output_description: 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}
      
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      A_1 A_2 ... A_N
attempt: import sys
  
  input = sys.stdin.readline
  
  N = int(input())
  A = list(map(int, input().split()))
  pos, neg, zero = [], [], []
  
  for Ai in A:
      if Ai > 0:
          pos.append(Ai)
      elif Ai < 0:
          neg.append(Ai)
      else:
          zero.append(0)
  
  if len(neg) == 0:
      neg += zero
  else:
      pos += zero
  
  ope = []
  
  if len(pos) > 0 and len(neg) > 0:
      now1 = pos[0]
  
      for i in range(1, len(neg)):
          ope.append((now1, neg[i]))
          now1 -= neg[i]
  
      now2 = neg[0]
  
      for i in range(1, len(pos)):
          ope.append((now2, pos[i]))
          now2 -= pos[i]
  
      ope.append((now1, now2))
      M = now1 - now2
  elif len(pos) == 0:
      neg.sort(reverse=True)
      now = neg[0]
  
      for i in range(1, len(neg)):
          ope.append((now, neg[i]))
          now -= neg[i]
  
      M = now
  else:
      pos.sort()
      now = pos[0]
  
      for i in range(1, len(pos) - 1):
          ope.append((now, pos[i]))
          now -= pos[i]
  
      ope.append((pos[-1], now))
      M = pos[-1] - now
  
  print(M)
  
  for x, y in ope:
      print(x, y)
  
problem_description: 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.
samples: [{"input": "3\n    1 -1 2", "output": "4\n    -1 1\n    2 -2\n    \n\nIf we choose x = -1 and y = 1 in the first operation, the set of integers\nwritten on the blackboard becomes (-2, 2).\n\nThen, if we choose x = 2 and y = -2 in the second operation, the set of\nintegers written on the blackboard becomes (4).\n\nIn this case, we have 4 as the final integer. We cannot end with a greater\ninteger, so the answer is 4.\n\n* * *"}, {"input": "3\n    1 1 1", "output": "1\n    1 1\n    1 0"}]