#include<cstdio>
#include<iostream>
#include<cmath>
#include<algorithm>
#include<string.h>
#include<iomanip>
#include<stack>
#include<deque>
#include<queue>
#include<vector>
#include<map>
#include<set>
#define ll               long long
#define endl             "\n"
using namespace std;
const ll mod = 1e9 + 7;
vector<ll>e[1000005];
ll n, t, k, p;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    cin >> n >> k;
    priority_queue<ll>a, b;
    ll ansa = 0, ansb = 0, numa = 0, numb = 0;
    for (int i = 1; i <= n; i++)
    {
        cin >> p;
        a.push(p);
    }
    for (int i = 1; i <= n; i++)
    {
        cin >> p;
        b.push(p);
    }
    while (a.size() && (numa <= k || numb <= k))
    {
        if (a.empty() || numa == k || (b.size() && a.top() < b.top()))
        {
            b.pop();
        }
        else
        {
            ansa += a.top();
            numa++;
            a.pop();
        }
        if (b.empty() || numb == k || (a.size() && b.top() < a.top()))
        {
            a.pop();
        }
        else
        {
            ansb += b.top();
            numb++;
            b.pop();
        }
    }
    cout << ansa - ansb;
    return 0;
}