#include <bits/stdc++.h>
using namespace std;

int maximumReward(int N, int K, vector<int> &C)
{
    priority_queue<int, vector<int>, greater<int>> min_heap; // min heap to calculate the maximum sum till i element
    priority_queue<int> max_heap;                            // max heap to calculate the minimum sum after i element

    int preSum = 0;
    int sufSum = 0;

    vector<int> prefix(2 * N, -1);
    vector<int> suffix(2 * N, 1e9);

    for (int i = 0; i < K; i++)
    {
        preSum += C[i];
        min_heap.push(C[i]);
    }
    prefix[K - 1] = preSum;

    for (int i = K; i < (2 * N); i++)
    {
        int top_ele = min_heap.top();
        if (C[i] > top_ele)
        {
            preSum -= top_ele;
            min_heap.pop();
            preSum += C[i];
            min_heap.push(C[i]);
        }
        prefix[i] = preSum;
    }

    for (int i = 2 * N - 1; i >= (2 * N - K); i--)
    {
        sufSum += C[i];
        max_heap.push(C[i]);
    }
    suffix[2 * N - K] = sufSum;

    for (int i = 2 * N - K - 1; i >= 0; i--)
    {
        int top_ele = max_heap.top();
        if (C[i] < top_ele)
        {
            sufSum -= top_ele;
            max_heap.pop();
            sufSum += C[i];
            max_heap.push(C[i]);
        }
        suffix[i] = sufSum;
    }

    int res = -1;
    for (auto i = K - 1; i < 2 * N - K; i++)
    {
        res = max(res, prefix[i] - suffix[i + 1]);
    }

    return res;
}

int main()
{
    int N, K;
    cin >> N >> K;

    vector<int> C(2 * N);
    for (int i = 0; i < 2 * N; i++)
    {
        cin >> C[i];
    }

    cout << maximumReward(N, K, C) << endl;
}