//  [javascript]
//↓見なくていいよ！ここから--------------------------------------------------
var read = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});
var obj;
var inLine = [];
read.on('line', function(input){inLine.push(input);});
read.on('close', function(){
  obj = init(inLine);
  myerr("-----start-----");
  var start = new Date();
  Main();
  var end = new Date() - start;
  myerr("----- end -----");
  myerr("time : " + (end) + "ms");
  myerr("memory : " + Math.round(process.memoryUsage().heapTotal / 1024) + "KB");
});
function nextInt(){return myconv(next(),1);} function nextStrArray(){return myconv(next(),2);}
function nextIntArray(){return myconv(next(),4);} function nextCharArray(){return myconv(next(),6);}
function next(){return obj.next();} function hasNext(){return obj.hasNext();}
function init(input){  
  var returnObj = {
    list : input, index : 0, max : input.length,
    hasNext : function(){return (this.index < this.max);},
    next : function(){if(!this.hasNext()){throw "ArrayIndexOutOfBoundsException これ以上ないよ";}else{var returnInput = this.list[this.index];this.index++;return returnInput;}}
  };
  return returnObj;
}
function myout(s){console.log(s);}
function myerr(s){console.error("debug:" + require("util").inspect(s,false,null));}
//[no]要素の扱い。数値型
//不明値、異常時:引数そのまま返す 1:数値へ変換
//2:半角SPで分割 4:半角SPで分割し、数値配列へ
//6:1文字で分割  7:1文字で分割し、数値配列へ
//8:半角SPで結合 9:改行で結合 0:文字なしで結合
function myconv(i,no){try{switch(no){case 1:return parseInt(i);case 2:return i.split(" ");case 4:return i.split(" ").map(Number);case 6:return i.split("");case 7:return i.split("").map(Number);case 8:return i.join(" ");case 9:return i.join("\n");case 0:return i.join("");default:return i;}}catch(e){return i;}}

//↑見なくていいよ！ここまで--------------------------------------------------
function Main(){
	var one = nextIntArray();
	var N = one[0];
	var K = one[1];
	var list = nextIntArray();
	var ruiseki = [0];
	var startIndex = list.indexOf(0);
	var output = Math.pow(10,15);
	if(startIndex != -1){
		//0がある
		K--;
		if(K == 0){
			myout(0);
			return;
		}
	}else if(list[0] > 0){
		//始点が左端
		myout(Math.abs(list[K - 1]));
		return;
	}else if(list[N - 1] < 0){
		//始点が右端
		myout(Math.abs(list[N - K]));
		return;
	}else{
		var tmpList = [];
		var isZero = false;
		for(var i = 0; i < N; i++){
			if(!isZero && list[i] > 0){
				tmpList.push(0);
				isZero = true;
				startIndex = i;
			}
			tmpList.push(list[i]);
		}
		list = tmpList;
		N++;
	}
	for(var i = 0; i < N - 1; i++){
		ruiseki.push(ruiseki[ruiseki.length - 1] + Math.abs(Math.abs(list[i]) - Math.abs(list[i + 1])));
	}
	var left = startIndex - 1;
	var leftCount = K;
	var right = startIndex + 1;
	var rightCount = K;
	while(left >= 0 && leftCount > 0){
		var tmpSum = ruiseki[startIndex] - ruiseki[left];
		if(startIndex - left < K){
			tmpSum += ruiseki[startIndex] - ruiseki[left];//折り返し
			tmpSum += ruiseki[startIndex + (K - (startIndex - left))] - ruiseki[startIndex];
		}
		output = Math.min(output, tmpSum);
		left--;
		leftCount--;
	}
	
	while(right < N && rightCount > 0){
		var tmpSum = ruiseki[right] - ruiseki[startIndex];
		if(right - startIndex < K){
			tmpSum += ruiseki[right] - ruiseki[startIndex];//折り返し
			tmpSum += ruiseki[startIndex] + ruiseki[startIndex - (K - (right - startIndex))];
		}
		output = Math.min(output, tmpSum);
		right++;
		rightCount--;
	}
	myout(output);
}