#include<bits/stdc++.h>
using namespace std;
#define pb emplace_back
typedef long long ll;
const int N=1e5+5;

int n,k,a[N],b[N];

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0),cout.tie(0);

    cin>>n>>k;
    for(int i=1;i<=n;i++) cin>>a[i];
    for(int i=1;i<=n;i++) cin>>b[i];

    sort(a+1,a+1+n);
    sort(b+1,b+1+n);

    int p1=n,p2=n;

    vector<int> s1,s2;
    for(int i=1;i<=2*n;i++) {
        if(i&1) {
            if(a[p1]>b[p2]) s1.pb(a[p1]),p1--;
            else p2--;
        } else {
            if(b[p2]>a[p1]) s2.pb(b[p2]),p2--;
            else p1--;
        }
    }

    ll sum1=0,sum2=0;
    for(int i=0;i<s1.size()&&i<k;i++) sum1+=s1[i];
    for(int i=0;i<s2.size()&&i<k;i++) sum2+=s2[i];

    cout<<sum1-sum2;
}