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

#define int long long

const int N = 1e5+100;
int n,k;
int a[N],b[N];

bool cmp(int x,int y){
	return x>y;
}

//int s1[N],s2[N];

signed main(){
	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+n+1,cmp); sort(b+1,b+n+1,cmp);
	int l = 1 , r = 1;
	int cnt1 = 0  , cnt2 = 0;
	int s1 = 0  ,s2 = 0;
	bool f = 1;
	while (1){
		if (l > n){
			if (f == 1) r++;
			else{
				if (cnt2 < k) cnt2++,s2+=b[r];
				r++;
			}
			goto This;
		}
		if (r > n){
			if (f == 0) l++;
			else{
				if (cnt1 < k) cnt1++,s1+=a[l];
				l++;
			}
			goto This;
		}
		if (a[l] >= b[r]){
			if (f == 1){
				if (cnt1 < k && a[l] > b[r]) cnt1++,s1+=a[l],l++;
				else r++;
			}
			else{
				if (cnt1 == k && cnt2 < k) s2+=b[r],r++,cnt2++;
				else l++;
			}
 		}
 		else{
 			if (f  == 0){
 				if (cnt2 < k) cnt2++,s2+=b[r],r++;
 				else l++;
			 }
			 else{
			 	if (cnt2 == k && cnt1 < k) s1+=a[l],l++,cnt1++;
			 	else r++;
			 }
		 }
		 This:;
		 if (l > n && r > n) break;
		 if (cnt1 == k && cnt2 == k) break;
		 f^=1;
	}
	cout<<s1-s2;
}