from typing import List, Tuple, Callable, TypeVar, Optional
import sys
import itertools
import heapq
import bisect
import math
from collections import deque, defaultdict
from functools import lru_cache, cmp_to_key

input = sys.stdin.readline

if __file__ != 'prog.py':
    sys.setrecursionlimit(10 ** 6)


def readints(): return map(int, input().split())
def readlist(): return list(readints())
def readstr(): return input()[:-1]
def readlist1(): return list(map(lambda x: int(x) - 1, input().split()))


class BIT:
    def __init__(self, N):
        self.N = N
        self.A = [0] * (N + 1)

    def add(self, i, x):
        """add x to i-th element (0-indexed)"""
        assert 0 <= i < self.N
        i += 1
        while i <= self.N:
            self.A[i] += x
            i += i & -i

    def sum(self, i):
        """return sum(A[:i])"""
        assert 0 <= i <= self.N
        s = 0
        while i > 0:
            s += self.A[i]
            i -= i & -i
        return s

    def range_sum(self, l, r):
        """return sum(A[l:r])"""
        return self.sum(r) - self.sum(l)



class BitVector:
    # reference: https://tiramister.net/blog/posts/bitvector/
    TABLE = bytes([
        0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
        1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
        1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
        2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
        1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
        2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
        2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
        3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
        1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
        2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
        2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
        3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
        2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
        3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
        3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
        4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
    ])

    def __init__(self, N):
        self.cnum = (N + 255) >> 8

        self.bit = bytearray(self.cnum << 5)
        self.chunk = [0] * (self.cnum + 1)
        self.blocks = bytearray(self.cnum << 5)

        self.built = False

    def set(self, pos):
        self.bit[pos >> 3] |= 1 << (pos & 7)

    def access(self, pos):
        return self.bit[pos >> 3] >> (pos & 7) & 1

    def popcount(self, num):
        return self.TABLE[num]

    def build(self):
        for i in range(self.cnum):
            k = i << 5
            for j in range(31):
                self.blocks[k + 1] = self.blocks[k] + self.popcount(self.bit[k])
                k += 1
            self.chunk[i + 1] = self.chunk[i] + self.blocks[k] + self.popcount(self.bit[k])
        self.built = True

    def rank(self, pos):
        assert self.built
        cpos, tmp = pos >> 8, pos & 255
        bpos, offset = tmp >> 3, tmp & 7

        i = cpos << 5 | bpos
        rest = self.bit[i] & ((1 << offset) - 1)
        return self.chunk[cpos] + self.blocks[i] + self.popcount(rest)

    def select(self, num):
        """return minimum i that satisfies rank(i) = num"""
        assert self.built
        if num == 0:
            return 0
        if self.rank(self.N) < num:
            return -1

        l = -1
        r = self.N
        while r - l > 1:
            c = (l + r) >> 1
            if self.rank(c) >= num:
                r = c
            else:
                l = c
        return r


class WaveletMatrix:
    # reference: https://miti-7.hatenablog.com/entry/2018/04/28/152259
    def __init__(self, A):
        self.nums = sorted(set(A))
        self.idx = {a: i for i, a in enumerate(self.nums)}
        self.A = [self.idx[a] for a in A]

        self.digit = (len(self.nums) - 1).bit_length()
        self.B = [None] * self.digit
        self.offset = [None] * self.digit
        self.start_index = [-1] * len(self.nums)

        T = self.A
        for k in range(self.digit)[::-1]:
            self.B[k] = BitVector(len(T) + 1)
            zeros = []
            ones = []
            for i, a in enumerate(T):
                if a >> k & 1:
                    self.B[k].set(i)
                    ones.append(a)
                else:
                    zeros.append(a)
            self.B[k].build()
            self.offset[k] = len(zeros)
            T = zeros + ones
        for i, a in enumerate(T):
            if self.start_index[a] < 0:
                self.start_index[a] = i

    def access(self, i):
        """return i-th value"""
        ret = 0
        cur = i
        for k in range(self.digit)[::-1]:
            if self.B[k].access(cur):
                ret |= (1 << k)
                cur = self.B[k].rank(cur) + self.offset[k]
            else:
                cur -= self.B[k].rank(cur)
        return self.nums[ret]

    def rank(self, i, x):
        """return the number of x's in [0, i) range"""
        x = self.idx.get(x)
        if x is None:
            return 0
        for k in range(self.digit)[::-1]:
            if x >> k & 1:
                i = self.B[k].rank(i) + self.offset[k]
            else:
                i -= self.B[k].rank(i)
        return i - self.start_index[x]

    def quantile(self, l, r, n):
        """return n-th (0-indexed) smallest value in [l, r) range"""
        assert 0 <= n < r - l
        ret = 0
        for k in range(self.digit)[::-1]:
            rank_l = self.B[k].rank(l)
            rank_r = self.B[k].rank(r)
            ones = rank_r - rank_l
            zeros = r - l - ones
            if zeros <= n:
                ret |= 1 << k
                l = rank_l + self.offset[k]
                r = rank_r + self.offset[k]
                n -= zeros
            else:
                l -= rank_l
                r -= rank_r
        return self.nums[ret]

    def range_freq(self, l, r, lower, upper):
        """return the number of values s.t. lower <= x < upper"""
        return self.range_freq_upper(l, r, upper) - self.range_freq_upper(l, r, lower)

    def prev_value(self, l, r, upper):
        """return maximum x s.t. x < upper in [l, r) range if exist, otherwise None"""
        cnt = self.range_freq_upper(l, r, upper)
        if cnt == 0:
            return None
        return self.quantile(l, r, cnt - 1)

    def next_value(self, l, r, lower):
        """return minimum x s.t. x >= lower in [l, r) range if exist, otherwise None"""
        cnt = self.range_freq_upper(l, r, lower)
        if cnt == r - l:
            return None
        return self.quantile(l, r, cnt)

    def range_freq_upper(self, l, r, upper):
        """return the number of values s.t. x < upper in [l, r) range"""
        if l >= r:
            return 0
        if upper > self.nums[-1]:
            return r - l
        if upper <= self.nums[0]:
            return 0
        upper = bisect.bisect_left(self.nums, upper)
        ret = 0
        for k in range(self.digit)[::-1]:
            rank_l = self.B[k].rank(l)
            rank_r = self.B[k].rank(r)
            ones = rank_r - rank_l
            zeros = r - l - ones
            if upper >> k & 1:
                ret += zeros
                l = rank_l + self.offset[k]
                r = rank_r + self.offset[k]
            else:
                l -= rank_l
                r -= rank_r
        return ret



N, K = readints()
A = readlist()
WM = WaveletMatrix(A)

cands = [0] * (N - K + 1)
task = defaultdict(list)
for i in range(N - K + 1):
    med = WM.quantile(i, i + K, K // 2)
    task[med].append(i)

nums = WM.nums
idx = defaultdict(list)
for i, a in enumerate(A):
    idx[a].append(i)

bit = BIT(N)
bit2 = BIT(N)
for k in nums:
    for i in task[k]:
        cands[i] += k * bit2.range_sum(i, i + K) - bit.range_sum(i, i + K)
    for i in idx[k]:
        bit.add(i, k)
        bit2.add(i, 1)
bit = BIT(N)
bit2 = BIT(N)
for k in nums[::-1]:
    for i in task[k]:
        cands[i] += bit.range_sum(i, i + K) - k * bit2.range_sum(i, i + K)
    for i in idx[k]:
        bit.add(i, k)
        bit2.add(i, 1)
print(min(cands))