output_description: If store A is closer, print `A`; if store B is closer, print `B`.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      x a b
attempt: # ABC071-C
  N = int(input())
  A_list = list(map(int, input().split()))
  
  A_set = set(A_list)
  A_set = sorted(A_set, reverse=True)
  
  side_list = [0, 0]
  
  for i in range(len(A_set)):  # 大きい順に取っていき，リストで個数を確認する
      if len(side_list) >= 4:
          break
      count = A_list.count(A_set[i])  # リストの個数を確認
      if count == 2 or count == 3:
          side_list.append(A_set[i])
      if count >= 4:
          side_list.append(A_set[i])
          side_list.append(A_set[i])
  
  side_list.sort(reverse=True)
  print(side_list[0] * side_list[1])
  
problem_description: Statement
  
  Snuke lives at position x on a number line. On this line, there are two stores
  A and B, respectively at position a and b, that offer food for delivery.
  
  Snuke decided to get food delivery from the closer of stores A and B. Find out
  which store is closer to Snuke's residence.
  
  Here, the distance between two points s and t on a number line is represented
  by |s-t|.
samples: [{"input": "5 2 7", "output": "B\n    \n\nThe distances between Snuke's residence and stores A and B are 3 and 2,\nrespectively. Since store B is closer, print `B`.\n\n* * *"}, {"input": "1 999 1000", "output": "A"}]