import sys
from collections import defaultdict, Counter, deque
from itertools import permutations, combinations, product, combinations_with_replacement, groupby, accumulate
import operator
from math import sqrt, gcd, factorial
# from math import isqrt, prod,comb  # python3.8用(notpypy)
from bisect import bisect_left, bisect_right
#from functools import lru_cache,reduce
#from heapq import heappush,heappop,heapify,heappushpop,heapreplace
#import numpy as np
#import networkx as nx
#from networkx.utils import UnionFind
#from numba import njit, b1, i1, i4, i8, f8
#from scipy.sparse import csr_matrix
#from scipy.sparse.csgraph import shortest_path, floyd_warshall, dijkstra, bellman_ford, johnson, NegativeCycleError
# numba例 @njit(i1(i4[:], i8[:, :]),cache=True) 引数i4配列、i8 2次元配列,戻り値i1
def input(): return sys.stdin.readline().rstrip()
def divceil(n, k): return 1+(n-1)//k  # n/kの切り上げを返す
def yn(hantei, yes='Yes', no='No'): print(yes if hantei else no)


def main():
    mod = 10**9+7
    mod2 = 998244353
    n, k = map(int, input().split())
    A = list(map(int, input().split())) + [10**16]
    accA = [0]+list(accumulate(A))
    ans = 10**20
    l = 0
    r = k
    for i in range(n):
        Ai = A[i]
        while max(abs(Ai-A[l]), abs(Ai-A[r-1])) >= max(abs(Ai-A[l+1]), abs(Ai-A[r])):
            l += 1
            r += 1
        """
        ng, ok = -1, 2*10**9+10  # abs(ok)以下でk個揃えられるか？
        while (abs(ok - ng) > 1):
            mid = (ok + ng) // 2
            r = bisect_right(A, Ai+mid)
            l = bisect_left(A, Ai-mid)
            if r-l >= k:
                ok = mid
            else:
                ng = mid
        r = bisect_right(A, Ai+ok)
        l = bisect_left(A, Ai-ok)
        """
        plusone = accA[r]-accA[i]-Ai * \
            (r-i)-accA[i]+accA[l]+Ai*(i-l)  # -ok*(k-(r-l))
        minusone = accA[n]-accA[r]-Ai*(n-r)-accA[l]+Ai*l  # +ok*(k-(r-l))
        ans = min(ans, plusone-minusone)
        # print(ans,l,r,ok,mid)
    print(ans)


if __name__ == '__main__':
    main()