Problem:
Score : 300 points

Problem 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.

Constraints

1 \leq N \leq 10^5

1 \leq K \leq N

x_i is an integer.

|x_i| \leq 10^8

x_1 < x_2 < ... < x_N

Input

Input is given from Standard Input in the following format:

N K
x_1 x_2 ... x_N

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

There may be a candle placed at coordinate 0.

Sample Input 4

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

Sample Output 4

10

Solution in JavaScript (Node.js 12.16.1) (judge verdict: Wrong Answer)

function Main(input) {
  input=input.split("\n");
  if(input[input.length-1]===''){
    input.pop();
  }
  const N=input[0].split(' ')[0]-0;
  const K=input[0].split(' ')[1]-0;
  const x=input[1].split(' ').map(e=>{
    return e-0;
  });
  var pointer=x.findIndex(e=>{
    return e=>0;
  })-K;
  if(pointer<0){
    pointer=0;
  }
  var temp;
  var ret=Infinity;
  for(var i=0;i<K;i++){
    if(pointer+i+K-1>=x.length){
      break;
    }
    if(x[pointer+i]*x[pointer+i+K-1]<0){
      temp=Math.min(-x[pointer+i],x[pointer+i+K-1])-x[pointer+i]+x[pointer+i+K-1];
    }else{
      temp=Math.max(Math.abs(x[pointer+i]),Math.abs(x[pointer+i+K-1]));
    }
    ret=Math.min(ret,temp);
  }
  console.log(ret);
      
}

//*この行以降は編集しないでください（標準入出力から一度に読み込み、Mainを呼び出します）
Main(require("fs").readFileSync("/dev/stdin", "utf8"));