#include <bits/stdc++.h>

using namespace std;

const int nax = 5000 + 10, INF = 1e9;
int n;
int a[nax], b[nax];

bool check(int x) {
	for (int i = 1; i <= n; ++i) {
		int ptr = 0;
		int ptr2 = n + 1;
		for (int j = n; j >= 1; --j) {
			if (b[j] >= a[i] + x) {
				ptr2 = j;
			}
		}
		for (int j = i; j <= n; ++j) {
			
			int me = j - i + 1;
			while (ptr < n && b[ptr + 1] <= a[j] - x) {
				ptr++;
			}
			//[1...ptr] [ptr2...n]
			int he = 0;
			if (ptr > ptr2) {
				he = n;
			} else {
				he = ptr + (n - ptr2 + 1);
			}
			if (he < me) return false;
		}
	}
	return true;
}

void solve() {
	cin >> n;
	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);
	sort(b + 1, b + n + 1);
	int low = 0, high = INF, mid;
	while (low <= high) {
		mid = (low + high) >> 1;
		if (check(mid)) {
			low = mid + 1;
		} else {
			high = mid - 1;
		}
	}
	cout << low - 1 << "\n";
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int t;
	cin >> t;
	while (t--) {
		solve();
	}
}