candles

Problem Statement

There are N candles placed on a number line. The i-th candle from the left is placed on coordinate xi. Here, x1 < x2 < ... < xN 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 amount of time to light K candles.

Constraints

  • 1 ≤ N ≤ 105
  • 1 ≤ K ≤ N
  • xi is an integer
  • |xi| ≤ 108
  • x1 < x2 < ... < xN

Input

Input is given from Standard Input in the following format:

N K
x1 x2 ... xN

Output

Print the minimum time required to light K candles.

Sample Input 1

5 3
-30 -10 10 20 50

Sample Output 1

40

He should move and light candles as follows:

  • Move from coordinate 0 to −10.
  • Light the second candle from the left.
  • Move from coordinate −10 to 10.
  • Light the third candle from the left.
  • Move from coordinate 10 to 20.
  • Light the fourth candle from the left.

Sample Input 2

3 2
10 20 30

Sample Output 2

20

Sample Input 3

1 1
0

Sample Output 3

0

Sample Input 4

8 5
-9 -7 -4 -3 1 2 3 4

Sample Output 4

10

Submitting .cpp to 'candles'


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Time Limit: 2 Seconds
Memory Limit: 1024MB
Your best score: 0
Source: ABC 107C

Subtask Score
1 100
2 0