#include <bits/stdc++.h>
#define x first
#define y second
using namespace std;
using ll=long long;
using pii=pair<int,int>;
using vi=vector<int>;
using vl=vector<ll>;
#define pb push_back
#define all(a) begin(a),end(a)

const int N=300010,MOD=1e9+7;
const char en='\n';
const ll LLINF=1ll<<60;

int t,n,a[N],b[N],cl[N],cr[N];

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cin>>t;
	while (t--)
	{
		cin>>n;
		for (int i=0;i<n;++i) cin>>a[i];
		for (int i=0;i<n;++i) cin>>b[i];
		sort(a,a+n);
		sort(b,b+n);
		int lo=0,hi=MOD;
		while (lo<hi)
		{
			int mid=(lo+hi+1)/2;
			int ccl=0;
			for (int i=0;i<n;++i)
			{
				while (ccl<n && b[ccl]<=a[i]-mid) ++ccl;
				cl[i]=ccl;
			}
			int ccr=0;
			for (int i=n-1;i>=0;--i)
			{
				while (ccr<n && b[n-ccr-1]>=a[i]+mid) ++ccr;
				cr[i]=ccr;
			}
			int pmi=MOD;
			bool ok=1;
			for (int i=0;i<n;++i)
			{
				pmi=min(pmi,cr[i]+i-1);
				if (pmi+cl[i]-i<0) ok=0;
			}
			if (ok) lo=mid;
			else hi=mid-1;
		}
		cout<<lo<<en;
	}
}