import os,sys,random,threading
#sys.exit() 退出程序
#sys.setrecursionlimit(10**6) #调整栈空间
from random import randint,choice,shuffle
#randint(a,b)从[a,b]范围随机选择一个数
#choice(seq)seq可以是一个列表,元组或字符串,从seq中随机选取一个元素
#shuffle(x)将一个可变的序列x中的元素打乱
from copy import deepcopy
from io import BytesIO,IOBase
from types import GeneratorType
from functools import lru_cache,reduce
#reduce(op,迭代对象)
from bisect import bisect_left,bisect_right
#bisect_left(x) 大于等于x的第一个下标
#bisect_right(x) 大于x的第一个下标
from collections import Counter,defaultdict,deque
from itertools import accumulate,combinations,permutations
#accumulate(a)用a序列生成一个累积迭代器，一般list化前面放个[0]做前缀和用
#combinations(a,k)a序列选k个 组合迭代器
#permutations(a,k)a序列选k个 排列迭代器
from heapq import  heapify,heappop,heappush
#heapify将列表转为堆
from typing import Generic,Iterable,Iterator,TypeVar,Union,List
from string import ascii_lowercase,ascii_uppercase,digits
#小写字母，大写字母，十进制数字
from math import ceil,floor,sqrt,pi,factorial,gcd,log,log10,log2,inf
#ceil向上取整，floor向下取整 ，sqrt开方 ，factorial阶乘
from decimal import Decimal,getcontext
#Decimal(s) 实例化Decimal对象,一般使用字符串
#getcontext().prec=100 修改精度
from sys import stdin, stdout, setrecursionlimit
input = lambda: sys.stdin.readline().rstrip("\r\n")
MI = lambda :map(int,input().split())
li = lambda :list(MI())
ii = lambda :int(input())
mod = int(1e9 + 7) #998244353
inf = 1<<60
py = lambda :print("YES")
pn = lambda :print("NO")
DIRS = [(0, 1), (1, 0), (0, -1), (-1, 0)]  # 右下左上
DIRS8 = [(0, 1), (1, 1), (1, 0), (1, -1), (0, -1), (-1, -1), (-1, 0),(-1, 1)]  # →↘↓↙←↖↑↗




n,k=li()

a=li()

if k==n:
    x=a[n//2]
    res=0
    for i in a:
        res+=abs(i-x)
    print(res)
    exit()

if k==0:
    x=a[0]
    r1=0
    for i in a:
        r1+=abs(i-x)
    x=a[-1]
    r2=0
    for i in a:
        r2+=abs(i-x)
    print(-max(r1,r2))
    exit()

a=[0]+a

f=[0]*(n+1) #f[i]表示a[i]到其他所有点的距离之和

pre=a[:]

for i in range(1,n+1):
    pre[i]+=pre[i-1]

for i in range(1,n+1):
    f[i]=(a[i]*i-pre[i])+(pre[n]-pre[i-1]-a[i]*(n-i+1)) 
    #[1,i]+[i,n]，i算两次没事的，不影响，还可以少点边界
    
g=[0]*(n+1)

l=1
r=k

def cal(l,r,i):
    return (a[i]*(i-l+1)-(pre[i]-pre[l-1]))+(pre[r]-pre[i-1]-a[i]*(r-i+1))

for i in range(1,n+1):
    if i==1:
        g[i]=cal(l,r,i)
    else:
        while r+1<=n and cal(l+1,r+1,i)<cal(l,r,i):
            l+=1
            r+=1
        g[i]=cal(l,r,i)

res=inf
for i in range(1,n+1):
    res=min(res,g[i]-(f[i]-g[i]))

# print(f,g)

print(res)