#ifdef DEBUG
//#define _GLIBCXX_DEBUG
#endif
//#pragma GCC optimize("O3")
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;

const ll mod = 1000000007;
//const ll mod = 998244353;

#define X first
#define Y second

ll pew(ll a, ll b)
{
    ll res = 1;
    while (b>0)
    {
        if (b&1) res = res*a%mod;
        b >>= 1;
        a = a*a%mod;
    }
    return res;
}


void solve()
{
    int n;
    cin >> n;
    vector<vector<ll>> a(n*2,vector<ll>(3));
    vector<set<pair<ll,ll>>> kek(3);
    vector<ll> mx(3);
    for (ll i=0;i<n;i++)
    {
        for (ll j=0;j<3;j++) cin >> a[i][j];
        for (ll j=0;j<3;j++) cin >> a[i+n][j];
        for (ll j=0;j<3;j++)
        {
            mx[j] = max(mx[j],a[i][j]);
            kek[j].insert({a[i][j],i});
        }
    }
    ll A = mod*mod;
    while (true)
    {
        ll p = -1, D = -1;
        for (int j=0;j<3;j++)
        {
            int w = kek[j].begin()->Y;
            if (mx[j]-a[w][j]>D)
            {
                D = mx[j]-a[w][j];
                p = w;
            }
        }
        A = min(A,D);
        if (p>=n) break;
        for (int j=0;j<3;j++)
        {
            kek[j].erase({a[p][j],p});
            kek[j].insert({a[p+n][j],p+n});
            mx[j] = max(mx[j],a[p+n][j]);
        }
    }
    cout << A << "\n";
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
//#ifdef DEBUG
    //freopen("input.txt", "r", stdin);
//#endif
    int T = 1;
    cin >> T;
    while (T--) solve();
    return 0;
}