output_description: Print \displaystyle \sum_{L=1}^{N-1} \sum_{R=L+1}^{N} X_{L,R}.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      P_1 P_2 \ldots P_N
attempt: N = int(input())
  c = list(map(int, input().split(" ")))
  V = []
  cnt = [0]
  
  
  def dfs(s):
      # print(V)
      if len(s) == 2:
          return min(s)
      b = dfs(s[:-1])
      a = dfs(s[1:])
  
      if s[:-1] not in V:
          cnt[0] += b
  
      if s[1:] not in V:
          cnt[0] += a
  
      V.append(s[1:])
      V.append(s[:-1])
      if a == b and a < s[0]:
          return min(s[0], s[-1])
      else:
          return max(a, b)
  
  
  t = dfs(c)
  print(cnt[0] + t)
  
problem_description: Statement
  
  Given is a permutation P of \\{1, 2, \ldots, N\\}.
  
  For a pair (L, R) (1 \le L \lt R \le N), let X_{L, R} be the second largest
  value among P_L, P_{L+1}, \ldots, P_R.
  
  Find \displaystyle \sum_{L=1}^{N-1} \sum_{R=L+1}^{N} X_{L,R}.
samples: [{"input": "3\n    2 3 1", "output": "5\n    \n\nX_{1, 2} = 2, X_{1, 3} = 2, and X_{2, 3} = 1, so the sum is 2 + 2 + 1 = 5.\n\n* * *"}, {"input": "5\n    1 2 3 4 5", "output": "30\n    \n\n* * *"}, {"input": "8\n    8 2 7 3 4 5 6 1", "output": "136"}]