from collections import defaultdict,deque
import sys,heapq,bisect,math,itertools,string,queue,datetime
sys.setrecursionlimit(10**8)
INF = float('inf')
mod = 10**9+7
eps = 10**-7
def inpl(): return list(map(int, input().split()))
def inpls(): return list(input().split())

N,K = inpl()
aa = inpl()

x0 = 0
x3 = 10**9+10
x1 = (x0*2+x3)//3
x2 = (x0+x3*2)//3

def f(m):
    aa_dush = list(map(lambda x:abs(x-m), aa))
    l = 0
    tmp = sum(aa_dush[:K])
    ans = tmp
    for r in range(K,N):
        tmp += aa_dush[r]
        tmp -= aa_dush[l]
        ans = min(tmp,ans)
        l += 1
    return ans

for i in range(100):
    y1 = f(x1)
    y2 = f(x2)
    if y1 > y2:
        x0 = x1
    else:
        x3 = x2
    x1 = (x0*2+x3)//3
    x2 = (x0+x3*2)//3

print(min(f(x0),f(x1),f(x2),f(x3)))