#pragma GCC optimize "O3"
#include<bits/stdc++.h>
using namespace std;
using LL=long long;
#define FOR(i,l,r) for(int i=(l);i<=(r);++i)
#define REP(i,n) FOR(i,0,(n)-1)
#define ssize(x) int(x.size())
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(x...) cerr<<"["#x"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(x)
#else
#define debug(...) {}
#endif

int main() {
	cin.tie(0)->sync_with_stdio(0);
	int tests;
	cin >> tests;
	REP (test, tests) {
		int n;
		cin >> n;
		vector<int> a(n), b(n);
		REP (i, n)
			cin >> a[i];
		REP (i, n)
			cin >> b[i];
		sort(a.begin(), a.end());
		sort(b.begin(), b.end());
		auto check = [&](int k) {
			debug(k);
			vector<int> pref(n), suff(n);
			REP (i, n) {
				pref[i] = int(upper_bound(b.begin(), b.end(), a[i] - k) - b.begin() - 1);
				suff[i] = int(lower_bound(b.begin(), b.end(), a[i] + k) - b.begin());
			}
			debug(pref);
			debug(suff);
			REP (l, n) {
				FOR (r, l, n - 1) {
					if (pref[r] + 1 + (n - suff[l]) < r - l + 1) {
						return false;
					}
				}
			}
			return true;
		};
		int bp = 0, bk = 1e9 + 1;
		while (bk - bp > 1) {
			int bs = (bp + bk) / 2;
			if (check(bs)) {
				bp = bs;
			}
			else {
				bk = bs;
			}
		}
		cout << bp << '\n';
	}
}