import sys
input = lambda : sys.stdin.readline().rstrip()

sys.setrecursionlimit(2*10**5+10)
write = lambda x: sys.stdout.write(x+"\n")
debug = lambda x: sys.stderr.write(x+"\n")
writef = lambda x: print("{:.12f}".format(x))


### 座標圧縮 (一次元)
from bisect import bisect_left
def press(l):
    """xs: ソートした座標値
    inds: lの各要素のxsにおけるインデックス
    """
    # xs[inds[i]]==l[i]となる
    xs = sorted(set(l))
    inds = [None] * len(l)
#     d = {}
    for i,item in enumerate(l):
        inds[i] = bisect_left(xs, item)
#         d[item] = inds[i]
    return xs, inds
class BIT:
    ### BIT binary
    def __init__(self, n, values=None):
        self.bit = [0]*(n+1)
        self.n = n
        self.total = 0
        if values is not None:
            for i,v in enumerate(values):
                self.add(i,v)
                self.total += v
    def check(self):
        l = []
        prv = 0
        for i in range(1,self.n+1):
            val = self.query(i)
            l.append(val-prv)
            prv = val
        print(" ".join(map(str, l)))
    #a1 ~ aiまでの和 O(logn)
    def query(self,i):
        res = 0
        while i > 0:
            res += self.bit[i]
            # res %= M
            i -= i&(-i)
        return res
    def get(self,i):
        return self.query(i+1) - self.query(i)
    #ai += x(logN)
    def add(self,i,x):
        i += 1
        if i==0:
            raise RuntimeError
        self.total += x
        while i <= self.n:
            self.bit[i] += x
            # self.bit[i] %= M
            i += i&(-i)
    def index(self, v):
        """a0,...,aiの和がv以上になる最小のindexを求める
        存在しないとき配列サイズを返す
        """
        if v <= 0:
            return 0
        if self.total<v:
            return self.n
        x = 0
        r = 1
        while r < self.n:
            r = r << 1;
        ll = r
        while ll>0:
            if x+ll<self.n and self.bit[x+ll]<v:
                v -= self.bit[x+ll]
                x += ll
            ll = ll>>1
        return x

n,k = list(map(int, input().split()))
a = list(map(int, input().split()))
xs, inds = press(a)
m = len(xs)
bit = BIT(m)
bit2 = BIT(m)
total = 0
for i in range(k):
    bit.add(inds[i], 1)
    bit2.add(inds[i], xs[inds[i]])
    total += a[i]
ans = float("inf")
for i in range(k,n+1):
    v = bit.index((k+1)//2)
    left = bit2.query(v)
    lnum = bit.query(v)
    right = total - left - bit2.get(v)
    rnum = k - lnum - bit.get(v)
    val = (xs[v]*lnum - left) + (right - xs[v]*rnum)
    ans = min(ans, val)
#     bit2.check()
#     print(left, right)
    if i==n:
        break
    bit.add(inds[i], 1)
    bit2.add(inds[i], a[i])
    bit.add(inds[i-k], -1)
    bit2.add(inds[i-k], -a[i-k])
    total += a[i] - a[i-k]
print(ans)