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 = list(map(int, input().split(" ")))
      X = list(map(int, input().split(" ")))
      output = solve(N, K, X)
      print(output)
      return
  
  
  # ________________________________________
  #  Solve
  # ________________________________________
  def solve(N, K, X):
      """
      解答のコード
      """
      oab_min = X[-1] - X[0]
  
      a_list = [i for i in range(len(X)) if X[i] >= 0]  # O(N)
      b_list = [i for i in range(len(X)) if X[i] < 0]  # O(N)
  
      if not a_list:
          # if a_list is empty
          ob = -X[b_list[K - 1]]
          oab_min = min(ob, oab_min)
      if not b_list:
          oa = X[a_list[K - 1]]
          oab_min = min(ob, oab_min)
      left = max(0, K - len(b_list))
      right = min(len(a_list), K)
      for i in range(left, right):
          # if a_list is empty, skip this process
          if (i == 0) and (a_list[0] != 0):
              ob = -X[b_list[K - 1]]
              oab_min = min(ob, oab_min)
          oa = X[a_list[i]]
          ob = abs(X[a_list[i] - K + 1])
          oab = min(oa, ob) + oa + ob
          oab_min = min(oab, oab_min)
      return oab_min
  
  
  # ________________________________________
  
  
  if __name__ == "__main__":
      main()
  
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"}]