mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    N, K = map(int, input().split())
    A = list(map(int, input().split()))

    if K == 0:
        ans1 = ans2 = 0
        for a in A[1:]:
            ans1 += A[0] - a
        for a in A[:-1]:
            ans2 -= A[-1] - a
        print(min(ans1, ans2))
        exit()

    l = 0
    r = N - K
    ix = 0
    cur = 0
    for i in range(K):
        cur += abs(A[i] - A[0])
    for i in range(K, N):
        cur -= abs(A[i] - A[0])
    ans = cur
    for _ in range(N - K + 1):
        while ix != N-1:
            d = A[ix+1] - A[ix]
            cur_new = cur
            cur_new -= l * d
            cur_new += (ix+1 - l) * d
            cur_new -= (l+K-1 - ix) * d
            cur_new += r * d
            if cur_new <= cur:
                cur = cur_new
                ix += 1
            else:
                break
        ans = min(ans, cur)
        cur -= 2 * abs(A[ix] - A[l])
        cur += 2 * abs(A[ix] - A[-r])
        l += 1
        r -= 1
        if ix < l:
            d = A[ix+1] - A[ix]
            ix += 1
            cur -= l * d
            cur += (ix + 1 - l) * d
            cur -= (l + K - 1 - ix) * d
            cur += r * d
    print(ans)


if __name__ == '__main__':
    main()