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: N = int(input())
  a = list(map(int, input().split()))
  p = [t for t in a if t >= 0]
  m = [t for t in a if t < 0]
  p.sort(reverse=True)
  m.sort()
  l = []
  # print(a)
  if len(p) == 0:
      u = m.pop()
      v = m.pop()
      l.append((u, v))
      p.append(u - v)
  if len(m) == 0 and len(p) >= 2:
      u = p.pop()
      v = p.pop()
      l.append((u, v))
      m.append(u - v)
  while len(p) >= 2:
      u = m.pop()
      v = p.pop()
      l.append((u, v))
      m.append(u - v)
  while len(m):
      t = p[0]
      u = m.pop()
      l.append((t, u))
      p[0] = t - u
  print(p[0])
  for res in l:
      print(*res)
  
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"}]