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()))
  d = list(map(int, input().split()))
  d_m = []
  d_p = [i for i in d if i >= 0 or d_m.append(i)]
  ret = -1
  for i in range(k):
      if len(d_p) >= i and len(d_m) >= k - i:
          dp_t = d_p[i - 1] if i > 0 else 0
          dm_t = -1 * d_m[-(k - i)] if i != 0 else 0
          if dp_t == 0:
              ret_t = dm_t
          elif dm_t == 0:
              ret_t = dp_t
          else:
              ret_t = dp_t + dm_t + min(dp_t, dm_t)
          #   print(i, k-i, dp_t, dm_t, ret_t)
          if ret > ret_t or ret < 0:
              ret = ret_t
  print(ret)
  
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"}]