#include<iostream>
#include<queue>
#include<cmath>
#include<algorithm>
using namespace std;
int n,m,ans=0x3f3f3f3f;
int a[100000+5];
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	for(int i=1;i<=n-m+1;i++){
		int j=m+i-1;
		ans=min(ans,min(abs(a[i])+abs(a[j]-a[i]),abs(a[j])+abs(a[j]-a[i])));
	}
	if(ans==0x3f3f3f3f) cout<<0<<endl;
	cout<<ans<<endl;
}
#include <iostream>
#include <stdio.h>
#include <string>
#include <algorithm>
#include <vector>
#include <math.h>
#include <numeric>
#include <queue>
#include <numeric>
#include <iomanip>
#include <sstream>
#include <cmath>
#include <map>
#include <functional>
#include <limits>
#include <set>
#include <stack>
#include <cctype>
#define rep(i,a,b) for((i)=a;i<(int)(b);i++)

#define AAA (1000000007) 


using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pairII;


ll gcd(ll a, ll b) {
	if (b == 0)return a;
	return gcd(b, a % b);
}

ll lcm(ll a, ll b) {
	return a / gcd(a, b) * b;
}
ll powD(ll a, ll b) {
	ll ans = 1;
	a %= AAA;
	for (int i = 0; i < b; i++)
	{
		ans *= a;
		ans %= AAA;
	}
	return ans;
}


int main() {
	int i, j, k;

	int N, M, K;


	vector<int> X;
	cin >> N >> K;
	rep(i, 0, N) {
		int x;
		cin >> x;
		X.push_back(x);
	}
	ll ans = abs(X[0])*2 + abs(X[N - 1])*2;

	rep(i, 0, N-K+1) {
		ll a = min(abs(X[i]), abs(X[i + K-1]));
		ll b = max(abs(X[i]), abs(X[i + K-1]));
		if (X[i] < 0 && X[i + K - 1]>0) {
			ans = min(ans, a * 2 + b);
		}
		else {
			ans = min(ans,b);
		}

	}
	cout << ans;
	return 0;
}