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 main(N, K, xs):
  
      if xs[0] >= 0:
          return xs[K - 1]
      if xs[-1] <= 0:
          return abs(xs[-1 * K])
  
      for i, x in enumerate(xs):
          if x == 0:
              xs.pop(i)
              if K == 1:
                  return 0
              K = K - 1
              N = N - 1
          if x > 0:
              zi = i
              break
  
      result = None
  
      if zi - K >= 0:
          result = xs[zi - K]
      if zi + K - 1 <= N - 1:
          if result == None:
              result = xs[zi + K - 1]
          result = min(result, xs[zi + K - 1])
  
      for i in range(K - 1):
          if zi - K + i + 1 < 0:
              continue
          if zi - 1 + i + 1 > N - 1:
              continue
          l = abs(xs[zi - K + i + 1])
          r = abs(xs[zi - 1 + i + 1])
          if result == None:
              result = 2 * min(l, r) + max(l, r)
          else:
              if result > 2 * min(l, r) + max(l, r):
                  result = 2 * min(l, r) + max(l, r)
      return result
  
  
  N, K = [int(i) for i in input().split(" ")]
  xs = [int(i) for i in input().split(" ")]
  
  print(main(N, K, xs))
  
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"}]