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: # coding: utf-8
  num_lec = int(input())
  l_lec = [list(map(int, input().split())) for i in range(num_lec)]
  
  l_set = set([])
  for lec in l_lec:
      l_set.add(lec[0])
      l_set.add(lec[1])
  
  all_dis = []
  for num in l_set:
      l_dis = []
      for lec in l_lec:
          if lec[0] <= num <= lec[1]:
              min_dis = 0
          else:
              dis_0 = num - lec[0]
              if dis_0 < 0:
                  dis_0 *= -1
              dis_1 = num - lec[1]
              if dis_1 < 0:
                  dis_1 *= -1
              if dis_0 > dis_1:
                  min_dis = dis_1
              else:
                  min_dis = dis_0
          l_dis.append(min_dis)
      sum_dis = sum(l_dis)
      all_dis.append(sum_dis)
  
  ans = min(all_dis)
  
  print(ans)
  
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"}]