output_description: Print the minimum cost to achieve connectivity.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      N
      l_1 r_1
      l_2 r_2
      :
      l_N r_N
attempt: n = int(input())
  a = [list(map(int, input().split())) for i in range(n)]
  
  
  def keisan(x):
      ans = 0
      for i, j in a:
          if x < i:
              ans += i - x
          elif x > j:
              ans += x - j
      return ans
  
  
  x0 = 0
  x3 = 1 << 32
  while x3 - x0 > 2:
      x1 = (x0 * 2 + x3) // 3
      x2 = (x0 + x3 * 2) // 3
      y1 = keisan(x1)
      y2 = keisan(x2)
      if y1 > y2:
          x0 = x1
      else:
          x3 = x2
  print(min(keisan(x0), keisan(x0 + 1), keisan(x0 + 2)))
  
problem_description: Statement
  
  AtCoDeer the deer found N rectangle lying on the table, each with height 1. If
  we consider the surface of the desk as a two-dimensional plane, the i-th
  rectangle i(1≤i≤N) covers the vertical range of [i-1,i] and the horizontal
  range of [l_i,r_i], as shown in the following figure:
  
  ![](https://atcoder.jp/img/arc070/46b7dc61fc2016c9b45f10db46c6fce9.png)
  
  AtCoDeer will move these rectangles horizontally so that all the rectangles
  are connected. For each rectangle, the cost to move it horizontally by a
  distance of x, is x. Find the minimum cost to achieve connectivity. It can be
  proved that this value is always an integer under the constraints of the
  problem.
samples: [{"input": "3\n    1 3\n    5 7\n    1 3", "output": "2\n    \n\nThe second rectangle should be moved to the left by a distance of 2.\n\n* * *"}, {"input": "3\n    2 5\n    4 6\n    1 4", "output": "0\n    \n\nThe rectangles are already connected, and thus no move is needed.\n\n* * *"}, {"input": "5\n    999999999 1000000000\n    1 2\n    314 315\n    500000 500001\n    999999999 1000000000", "output": "1999999680\n    \n\n* * *"}, {"input": "5\n    123456 789012\n    123 456\n    12 345678901\n    123456 789012\n    1 23", "output": "246433\n    \n\n* * *"}, {"input": "1\n    1 400", "output": "0"}]