mod io {
    #[macro_export]
    macro_rules! scan {
        ($r:expr, [$t:tt; $n:expr]) => ((0..$n).map(|_| scan!($r, $t)).collect::<Vec<_>>());
        ($r:expr, ($($t:tt),*)) => (($(scan!($r, $t)),*));
        ($r:expr, [u8]) => (io::scan($r).into_bytes());
        ($r:expr, $t:ty) => (io::scan($r).parse::<$t>().unwrap());
    }

    use std::io::{BufRead, ErrorKind};

    pub fn scan<R: BufRead>(r: &mut R) -> String {
        let mut res = Vec::new();
        loop {
            let buf = match r.fill_buf() {
                Ok(buf) => buf,
                Err(e) if e.kind() == ErrorKind::Interrupted => continue,
                Err(e) => panic!(e), 
            };
            let (done, i) = match buf.iter().position(u8::is_ascii_whitespace) {
                Some(i) => (res.len() + i > 0, i),
                None => (buf.is_empty(), buf.len()),
            };
            res.extend_from_slice(&buf[..i]);
            r.consume(i + 1);
            if done { return res.into_iter().map(char::from).collect(); }
        }
    }
}

use std::io::{BufRead, Write};

fn run<R: BufRead, W: Write>(reader: &mut R, writer: &mut W) {
    let (n, k) = scan!(reader, (usize, usize));
    let a = scan!(reader, [i64; n]);

    let mut ans = {
        let x = a[0];
        let plus = a.iter().map(|a| (x - a).abs()).take(k).sum::<i64>();
        let minus = a.iter().map(|a| (x - a).abs()).skip(k).sum::<i64>();
        plus - minus
    };

    let mut sum = ans;
    let (mut l, mut r) = (0, k);
    let mut p = &a[0];
    for (i, x) in a.iter().enumerate().skip(1) {
        let d = x - p;

        sum -= (l + (r.max(i) - i) + (i - r.min(i))) as i64 * d;
        sum += ((i.min(r) - l) + (n - r.max(i))) as i64 * d;

        while r < n && (x - a[l]).abs() > (x - a[r]).abs() {
            sum -= (x - a[l]).abs() * 2;
            sum += (x - a[r]).abs() * 2;
            l += 1;
            r += 1;
        }

        ans = ans.min(sum);
        p = x;
    }

    writeln!(writer, "{}", ans).ok();
}

fn main() {
    let (stdin, stdout) = (std::io::stdin(), std::io::stdout());
    let mut reader = std::io::BufReader::new(stdin.lock());
    let mut writer = std::io::BufWriter::new(stdout.lock());
    run(&mut reader, &mut writer);
}