output_description: Print \sum_{i=1}^{N-1}\sum_{j=i+1}^{N} A_i A_j, modulo (10^9+7).
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      A_1 \ldots A_N
attempt: n = int(input(''))
  adl = input('')
  
  a = list(map(int,adl.split(' ')))
  
  number = 0
  
  mod0 = 1000000000
  mod1 = 7
  
  amari = 0
  
  
  
  for i in range(n):
      aa = 0
      for e in range(n-i-1):
          j = i+e+1
          if i != j:
              aa = aa + a[j]
      number = number + (a[i] * aa)
  amari0 = number % mod0
  amari1 = number % mod1
  amari = amari0 + amari1
  print(amari)
  
problem_description: Statement
  
  Given are N integers A_1,\ldots,A_N.
  
  Find the sum of A_i \times A_j over all pairs (i,j) such that 1\leq i < j \leq
  N, modulo (10^9+7).
samples: [{"input": "3\n    1 2 3", "output": "11\n    \n\nWe have 1 \\times 2 + 1 \\times 3 + 2 \\times 3 = 11.\n\n* * *"}, {"input": "4\n    141421356 17320508 22360679 244949", "output": "437235829"}]