import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.util.NoSuchElementException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		Scanner in = new Scanner(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		TaskC solver = new TaskC();
		solver.solve(1, in, out);
		out.close();
	}

	static class TaskC {
		public void solve(int testNumber, Scanner sc, PrintWriter out) {

			int n = sc.nextInt();
			int k = sc.nextInt();
			long[] x = sc.nextLongArray(n);
			long min = 1145141919810364364L;
			for (int i = 0; i <= n - k; i++) {
				if (0 <= x[i]) {
					min = Math.min(min, x[i + k - 1]);
				} else if (x[i + k - 1] <= 0) {
					min = Math.min(min, -x[i]);
				} else {
					min = Math.min(min, (x[i + k - 1] - x[i]) + Math.min(x[i + k - 1], -x[i]));
				}

			}
			out.println(min);

		}

	}

	static class Scanner {
		private final InputStream in;
		private final byte[] buffer;
		private int ptr;
		private int buflen;

		public Scanner(InputStream in) {
			this.in = in;
			this.buffer = new byte[1024];
			this.ptr = 0;
			this.buflen = 0;
		}

		private boolean hasNextByte() {
			if (ptr < buflen) return true;
			else {
				ptr = 0;
				try {
					buflen = in.read(buffer);
				} catch (IOException e) {
					e.printStackTrace();
				}
				if (buflen <= 0) return false;
			}
			return true;
		}

		private byte readByte() {
			if (hasNextByte()) return buffer[ptr++];
			return -1;
		}

		private boolean isPrintableChar(byte c) {
			return '!' <= c && c <= '~';
		}

		private void skipUnprintable() {
			while (hasNextByte() && !isPrintableChar(buffer[ptr])) {
				ptr++;
			}
		}

		public boolean hasNext() {
			skipUnprintable();
			return hasNextByte();
		}

		public int nextInt() {
			if (!hasNext()) throw new NoSuchElementException();
			int n = 0;
			boolean minus = false;
			byte b = readByte();
			if (b == '-') {
				minus = true;
				b = readByte();
			}
			if (b < '0' || '9' < b) throw new NumberFormatException();
			while (true) {
				if ('0' <= b && b <= '9') {
					n *= 10;
					n += b - '0';
				} else if (b == -1 || !isPrintableChar(b)) {
					return minus ? -n : n;
				} else {
					throw new NumberFormatException();
				}
				b = readByte();
			}
		}

		public long nextLong() {
			if (!hasNext()) throw new NoSuchElementException();
			long n = 0;
			boolean minus = false;
			byte b = readByte();
			if (b == '-') {
				minus = true;
				b = readByte();
			}
			if (b < '0' || '9' < b) throw new NumberFormatException();
			while (true) {
				if ('0' <= b && b <= '9') {
					n *= 10;
					n += b - '0';
				} else if (b == -1 || !isPrintableChar(b)) {
					return minus ? -n : n;
				} else {
					throw new NumberFormatException();
				}
				b = readByte();
			}
		}

		public long[] nextLongArray(int n) {
			long[] a = new long[n];
			for (int i = 0; i < n; i++) {
				a[i] = nextLong();
			}
			return a;
		}

	}
}



Measured memory_bytes: 22832