output_description: Print the minimum time required to light K candles.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N K
      x_1 x_2 ... x_N
attempt: def update():
      cost = list(map(abs, candles))
      min_cost_index = cost.index(min(cost))
      print(min_cost_index)
      start_index = max(0, min_cost_index - K)
      end_index = min(N, min_cost_index + K)
      new_candles = candles[start_index:end_index]
      return new_candles
  
  
  def compute_cost(point_candles):
      if point_candles[0] * point_candles[-1] >= 0:
          return max(abs(point_candles[0]), abs(point_candles[-1]))
      else:
          return (
              point_candles[-1]
              - point_candles[0]
              + min(abs(point_candles[0]), abs(point_candles[-1]))
          )
  
  
  N, K = list(map(int, input().strip().split(" ")))
  candles = list(map(int, input().strip().split(" ")))
  
  
  candles = update()
  
  N = len(candles)
  min_cost = None
  patterns = N - K + 1
  
  
  for start_index in range(patterns):
      cost = compute_cost(candles[start_index : start_index + K])
      if min_cost == None or min_cost > cost:
          min_cost = cost
  print(min_cost)
  
problem_description: Statement
  
  There are N candles placed on a number line. The i-th candle from the left is
  placed on coordinate x_i. Here, x_1 < x_2 < ... < x_N holds.
  
  Initially, no candles are burning. Snuke decides to light K of the N candles.
  
  Now, he is at coordinate 0. He can move left and right along the line with
  speed 1. He can also light a candle when he is at the same position as the
  candle, in negligible time.
  
  Find the minimum time required to light K candles.
samples: [{"input": "5 3\n    -30 -10 10 20 50", "output": "40\n    \n\nHe should move and light candles as follows:\n\n  * Move from coordinate 0 to -10.\n  * Light the second candle from the left.\n  * Move from coordinate -10 to 10.\n  * Light the third candle from the left.\n  * Move from coordinate 10 to 20.\n  * Light the fourth candle from the left.\n\n* * *"}, {"input": "3 2\n    10 20 30", "output": "20\n    \n\n* * *"}, {"input": "1 1\n    0", "output": "0\n    \n\n  * There may be a candle placed at coordinate 0.\n\n* * *"}, {"input": "8 5\n    -9 -7 -4 -3 1 2 3 4", "output": "10"}]