#include <bits/stdc++.h>

using namespace std;

vector<int> Match(vector<vector<int>>& graph, int n, int m) {
    vector<int> l(n, -1), r(m, n), q, dist;

    function<bool(int)> dfs = [&](int u) {
        if(u == n) return true;
        int d = dist[u]; dist[u] = -1;
        for(auto v : graph[u]) {
            if(dist[r[v]] == d + 1 && dfs(r[v])) {
                return l[u] = v, r[v] = u, true;
            }
        }
        return false;
    };

    while(true) {
        dist.assign(n + 1, -1);q.clear();
        for(int i = 0; i < n; ++i) {
            if(l[i] == -1) {
                dist[i] = 0, q.push_back(i);
            }
        }
        for(int i = 0; i < (int)q.size(); ++i) {
            int u = q[i]; if(u == n) break;
            for(auto v: graph[u]) {
                if(dist[r[v]] == -1) {
                    dist[r[v]] = 1 + dist[q[i]], q.push_back(r[v]);
                }
            }
        }
        if(dist[n] == -1) break;
        for(int i = 0; i < n; ++i) {
            if(l[i] == -1) {
                dfs(i);
            }
        }
    }
    return l;
}

bool check(const vector<int> &a, const vector<int> &b, int delta) {
    vector<vector<int>> graph(a.size());
    for(int i = 0; i < a.size(); i++) {
        for(int j = 0; j < b.size(); j++) {
            if(abs(a[i] - b[j]) >= delta) {
                graph[i].push_back(j);
            }
        }
    }
    auto l =  Match(graph, a.size(), b.size());
    
    for(auto &it: l) {
        if(it == -1) {
            return false;
        }
    }

    return true;
}

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

    int t;
    cin >> t;
    while(t--) {

        int n;
        cin >> n;

        vector<int> a(n), b(n);
        int __max = 0;

        for(auto &it: a) {
            cin >> it;
            __max = max(__max, it);
        }
        
        for(auto &it: b) {
            cin >> it;
            __max = max(__max, it);
        }

        int curr = 0;
        for(int h = (1 << 29); h; h >>= 1) {
            if(curr + h <= __max && check(a, b, curr + h)) {
                curr += h;
            }
        }

        cout << curr << "\n";
    }

    return 0;
}