#include <iostream>
#include <cstring>
#include <cmath>
#include <cstdio>
#include <climits>
#include <ctime>
#include <cassert>
#include <cctype>
#include <algorithm>
#include <numeric>
#include <map>
#include <set>
#include <queue>
#include <string>
#include <vector>
#include <bitset>

#define X first
#define Y second
#define pb push_back
#define bit(x) (1 << (x))
#define bnum(x) (__builtin_popcount(x))
#define all(x) (x).begin(), (x).end()
#define mset0(x) memset((x), 0, sizeof((x)))
#define mset1(x) memset((x), -1, sizeof((x)))
#define LET(x,a) __typeof(a) x(a)
#define REP(v,it) for( LET(it,v.begin()) ; it != v.end() ; it++)
#define sz(x) ((int)(x.size()))
#define PQ priority_queue
#define sqr(x) ((x) * (x))

using namespace std;
typedef long long LL;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pii> vpii;

template <class T> inline void chkmin(T &a, T b) {
    if (b < a) a = b;
}
template <class T> inline void chkmax(T &a, T b) {
    if (a < b) a = b;
}

const int MX = 200005;
int a[MX], b[MX];
LL sa[MX], sb[MX];

int main() {
    
    int T;
    int n, m;
    int i, j;
    
    for (scanf("%d", &T); T--; ) {
        scanf("%d%d", &n, &m);
        for (i = 1; i <= n; i++) scanf("%d", a + i);
        for (j = 1; j <= m; j++) scanf("%d", b + j);
        sort(a + 1, a + n + 1);
        sort(b + 1, b + m + 1);
        for (i = 1; i <= n; i++) sa[i] = sa[i - 1] + a[i];
        for (j = 1; j <= m; j++) sb[j] = sb[j - 1] + b[j];
        
        LL ans = 0;
        int cur = min(n, m);
        for (i = n; i; i--) {
            int id = upper_bound(b + 1, b + m + 1, a[i]) - b;
            id--;
            chkmin(cur, id);
            if (cur <= 0) break;
            
            chkmax(ans, sa[n] - sa[i - 1] - sb[n - i + 1]);
            cur--;
        }
        
        cout << ans << endl;
    }
    
    return 0;
}