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: N, K = list(map(int, input().split(" ")))
  l = list(map(int, input().split(" ")))
  minuss = [0] + [-i for i in l if i < 0][::-1]
  pluss = [0] + [i for i in l if i >= 0]
  # minuss から k本、plussからK-k本取る(短い方を折り返すので2倍)
  ans = 1e16  # ?
  if pluss == [0]:  # 4 2 [-4, -3 , -2, -1]
      pluss = minuss
      minuss = [0]
  for k in range(K):
      if k >= len(minuss) or K - k >= len(pluss):
          continue
      ans = min(ans, min(minuss[k] * 2 + pluss[K - k], minuss[k] + pluss[K - k] * 2))
  print(ans)
  
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"}]