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: S = input()
  A = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"] 
  B = [0]*26
  flag = -1
  
  for i in range(len(S)):
    
    for j in range(len(A)):
      if S[i] == A[j]:
        B[j] += 1
        break
    
    if i == len(S)
      break
  
  for k in range(B):
    if B[k] == 0
      print(A[k])
      flag = 1
      break
      
  if flag == -1:
    print("none")
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"}]