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 = map(int, input().split())
  x = list(map(int, input().split()))
  b = None
  
  for i in range(n):
      if x[i] == 0:
          b = i
          start = True
          break
      elif x[i] > 0:
          b = i
          start = False
          break
  
  
  if not b:
      m = abs(x[-k])
  
  else:
      if start:
          del x[b]
          k -= 1
          n -= 1
  
      if k == 0:
          m = 0
      else:
          if b >= k:
              m1 = abs(x[b - k])
          else:
              m1 = None
  
          if n - b >= k:
              m2 = abs(x[b + k - 1])
          else:
              m2 = None
  
          m = max(abs(2 * x[0]), abs(2 * x[-1]))
          for i in range(1, k):
              if b - i >= 0 and b - i + k - 1 < n:
                  m = min(
                      2 * abs(x[b - i]) + abs(x[b - i + k - 1]),
                      abs(x[b - i]) + 2 * abs(x[b - i + k - 1]),
                      m,
                  )
  
          if m1:
              m = min(m, m1)
          if m2:
              m = min(m, m2)
  
  print(m)
  
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"}]