#include <bits/stdc++.h>

using namespace std;

int t, n;

int a[10005];
int b[10005];

int par[10005];
bool viz[10005];
vector<int> v[10005];


bool tryMatch(int p, int avoid=-1)
{
    if(viz[p])
        return false;

    viz[p] = true;

    for(int it : v[p])
    {
        if(it == avoid)
            continue;

        if(par[it] == 0)
        {
            par[p] = it;
            par[it] = p;
            return true;
        }
    }

    for(int it : v[p])
    {
        if(it == avoid)
            continue;

        if(tryMatch(par[it], it))
        {
            par[p] = it;
            par[it] = p;
            return true;
        }
    }

    return false;
}

int match()
{
    int ans = 0;
    bool ok = true;

    for(int i=1;i<=2*n;i++)
        par[i] = 0;

    while(ok)
    {
        ok = false;

        for(int i=1;i<=n;i++)
            viz[i] = false;

        for(int i=1;i<=n;i++)
        {
            if(par[i] || viz[i])
                continue;

            if(tryMatch(i))
            {
                ans++;
                ok = true;
            }
        }
    }

    return ans;
}

bool ok(int minDif)
{
    for(int i=1;i<=n;i++)
        v[i].clear();

    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
            if(abs(a[i] - b[j]) >= minDif)
            {
                //cout<<"m add "<<i<<' '<<j<<'\n';
                v[i].push_back(n+j);
            }

    //cout<<"match is "<<match()<<'\n';
    return match() == n;
}

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

        cin>>n;

        for(int i=1;i<=n;i++)
            cin>>a[i];

        for(int i=1;i<=n;i++)
            cin>>b[i];

        //cout<<ok(11)<<'\n';
        //return 0;

        int st=0, dr=1e9, mij, last = 0;

        while(st <= dr)
        {
            mij = (st+dr)/2;

            if( ok(mij) )
            {
                last = mij;
                st = mij+1;
            }

            else
                dr = mij-1;
        }

        cout<<last<<'\n';
    }
    return 0;
}