// ---------- begin Foldable Deque ----------
pub struct FoldableDeque<T, F> {
    front: Vec<(T, T)>,
    back: Vec<(T, T)>,
    op: F,
}

#[allow(dead_code)]
impl<T, F> FoldableDeque<T, F>
where
    T: Clone,
    F: Fn(&T, &T) -> T,
{
    fn new(op: F) -> Self {
        FoldableDeque {
            front: Vec::new(),
            back: Vec::new(),
            op: op,
        }
    }
    fn find(&self) -> Option<T> {
        match (self.front.last(), self.back.last()) {
            (Some(a), Some(b)) => Some((self.op)(&a.1, &b.1)),
            (Some(a), None) => Some(a.1.clone()),
            (None, Some(b)) => Some(b.1.clone()),
            (None, None) => None,
        }
    }
    fn clear(&mut self) {
        self.front.clear();
        self.back.clear();
    }
    fn len(&self) -> usize {
        self.front.len() + self.back.len()
    }
    fn is_empty(&self) -> bool {
        self.len() == 0
    }
    fn push_back(&mut self, val: T) {
        let sum = self
            .back
            .last()
            .map_or_else(|| val.clone(), |p| (self.op)(&p.1, &val));
        self.back.push((val, sum));
    }
    fn push_front(&mut self, val: T) {
        let sum = self
            .front
            .last()
            .map_or_else(|| val.clone(), |p| (self.op)(&val, &p.1));
        self.front.push((val, sum));
    }
    fn pop_front(&mut self) -> Option<T> {
        if self.front.is_empty() {
            let a = self.back.clone();
            let m = (self.back.len() + 1) / 2;
            self.back.clear();
            let (f, b) = a.split_at(m);
            for v in f.iter().rev() {
                self.push_front(v.0.clone());
            }
            for v in b.iter() {
                self.push_back(v.0.clone());
            }
        }
        self.front.pop().map(|p| p.0)
    }
    fn pop_back(&mut self) -> Option<T> {
        if self.back.is_empty() {
            let a = self.front.clone();
            let m = (self.front.len() + 1) / 2;
            self.front.clear();
            let (f, b) = a.split_at(m);
            for v in b.iter() {
                self.push_front(v.0.clone());
            }
            for v in f.iter().rev() {
                self.push_back(v.0.clone());
            }
        }
        self.back.pop().map(|p| p.0)
    }
    fn front(&self) -> Option<&T> {
        self.front
            .last()
            .map_or_else(|| self.back.get(0).map(|p| &p.0), |p| Some(&p.0))
    }
    fn back(&self) -> Option<&T> {
        self.back
            .last()
            .map_or_else(|| self.front.get(0).map(|p| &p.0), |p| Some(&p.0))
    }
}
// ---------- end Foldable Deque ----------
// ---------- begin input macro ----------
// reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, bytes) => {
        read_value!($iter, String).bytes().collect::<Vec<u8>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
// ---------- end input macro ----------

fn merge(a: &(i64, i64), b: &(i64, i64)) -> (i64, i64) {
    (a.0 + b.0, a.1 + b.1)
}

fn run() {
    input! {
        n: usize,
        k: usize,
        a: [i64; n],
    }
    let mut left_minus = FoldableDeque::new(merge);
    let mut left_plus = FoldableDeque::new(merge);
    let mut right_plus = FoldableDeque::new(merge);
    let mut right_minus = FoldableDeque::new(merge);
    for a in a.iter().take(k) {
        right_plus.push_back((*a, 1));
    }
    for a in a.iter().skip(k) {
        right_minus.push_back((*a, 1));
    }
    let find = |x: i64, p: (i64, i64)| -> i64 {
        x * p.1 - p.0
    };
    let x = a[0];
    let mut ans = 0;
    ans += left_minus.find().map_or(0, |p| -find(x, p));
    ans += left_plus.find().map_or(0, |p| find(x, p));
    ans += right_plus.find().map_or(0, |p| -find(x, p));
    ans += right_minus.find().map_or(0, |p| find(x, p));
    for i in 1..n {
        if right_plus.is_empty() {
            right_plus.push_back(right_minus.pop_front().unwrap());
        }
        left_plus.push_back(right_plus.pop_front().unwrap());
        let x = a[i];
        while left_plus.len() > 0 && right_minus.len() > 0 {
            let p = left_plus.front().unwrap().0;
            let q = right_minus.front().unwrap().0;
            if x - p >= q - x {
                left_minus.push_back(left_plus.pop_front().unwrap());
                right_plus.push_back(right_minus.pop_front().unwrap());
            } else {
                break;
            }
        }
        let mut val = 0;
        val += left_minus.find().map_or(0, |p| -find(x, p));
        val += left_plus.find().map_or(0, |p| find(x, p));
        val += right_plus.find().map_or(0, |p| -find(x, p));
        val += right_minus.find().map_or(0, |p| find(x, p));
        ans = ans.min(val);
    }
    println!("{}", ans);
}

fn main() {
    run();
}