#include <bits/stdc++.h>
#define pii pair <int, int>

using namespace std;

int NL, NR;
vector <int> vs[5001];
int lmatch[5001];
int rmatch[5001];
int visited[5001], iter;
int a[5001], b[5001];

bool dfs(int u)
{
    if(visited[u] < iter){
        visited[u] = iter;
        for(int v : vs[u]){
            if(rmatch[v] == -1 || dfs(rmatch[v])){
                lmatch[u] = v;
                rmatch[v] = u;
                return true;
            }
        }
    }
    return false;
}

int maxmatching(){
    fill(lmatch, lmatch + NL, -1);
    fill(rmatch, rmatch + NR, -1);
    int m = 0, dm = 1;
    while(dm){
        dm = 0;
        iter++;
        for(int u = 0; u < NL; u++) if(lmatch[u] == -1)
            dm += dfs(u);
        m += dm;
    }
    return m;
}

bool verif(int mini)
{
    for(int i = 0; i < NL; i++)
        vs[i].clear();
    for(int i = 0; i < NL; i++)
        for(int j = 0; j < NR; j++)
            if(abs(a[i] - b[j]) >= mini)
                vs[i].push_back(j);
    int x = maxmatching();
    //cout << x << " ";
    return x == NL;

}

void solve() {
    int n;
    cin >> n;
    NL = NR = n;
    for(int i = 0; i < n; i++)
        cin >> a[i];
    for(int i = 0; i < n; i++)
        cin >> b[i];
    int r = -1, pas = 1 << 29;
    while(pas)
    {
        if(verif(r + pas))
            r += pas;
        pas /= 2;
    }
    cout << r << '\n';
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);

#ifdef LOCAL
    freopen("test.in", "r", stdin);
    freopen("test.out", "w", stdout);
#else

#endif
    int T = 1;
    cin >> T;
    while(T--) {
        solve();
    }
    return 0;
}