#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <cassert>

#define dig(...) fprintf(stderr, __VA_ARGS__)

template <class TAT>
void read(TAT &a)
{
    static char cc;
    static bool fff;
    while (((cc = getchar()) < '0' || cc > '9') && cc != '-');
    if (cc == '-') fff = 1, a = 0;
    else fff = 0, a = cc - 48;
    while ((cc = getchar()) >= '0' && cc <= '9') a = a * 10 + cc - 48;
    if (fff) a = -a;

}
template <class TAT>
void write(TAT a)
{
    static char cc[25];
    static int ct;
    if (a < 0) putchar('-'), a = -a;
    if (a == 0) {putchar('0'); return;}
    ct = 0;
    while (a) cc[++ct] = a % 10 + 48, a /= 10;
    while (ct) putchar(cc[ct--]);
}
void begin()
{
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
}
void end()
{
    fclose(stdin);
    fclose(stdout);
}

using namespace std;

const int maxn = 100005;

int n, m;
int A[maxn];
int B[maxn];

void Init()
{
    read(n), read(m);
    for (int i = 1; i <= n; ++i) read(A[i]);
    for (int i = 1; i <= m; ++i) read(B[i]);
}

void Solve()
{
    register long long S = 0;
    register long long Max = -2e9;
    register int cnt = 0;
    register int nt = 0, last = 0;
    sort(A + 1, A + 1 + n);
    sort(B + 1, B + 1 + m);
    for (int i = 1; i <= n; ++i)
    {
        if (nt == m) break;
        if (A[i] >= B[nt + 1])
        {
            ++cnt;
            ++nt;
        }
    }
    for (int i = n, j = 1; cnt >= 1; --i, ++j, --cnt)
    {
        S += A[i] - B[j];
        Max = max(Max, S);
    }
    cout << Max << endl;
}

int main()
{
    register int T;
    read(T);
    while (T--)
    {
        Init();
        Solve();
    }
    return 0;
}