#include <iostream>

#include <stack>
#include <queue>
#include <deque>
#include <vector>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>

#include <cmath>
#include <algorithm>

#include <fstream>

using namespace std;


bool rect(pair < int, int > a, pair < int, int > b, vector < pair < int, int > > &x) {
    bool ok = true;
    for (int i = 0; i < x.size(); ++i) {
        //bool temp_ok = true;
        if (a.first == x[i].first && a.second <= x[i].second  && x[i].second <= b.second) {
            continue;
        }
        if (b.first == x[i].first && a.second <= x[i].second  && x[i].second <= b.second) {
            continue;
        }
        if (a.second == x[i].second && a.first <= x[i].first  && x[i].first <= b.first) {
            continue;
        }
        if (b.second == x[i].second && a.first <= x[i].first  && x[i].first <= b.first) {
            continue;
        }
        ok = false;
    }
    return ok;
}

int main()
{
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);

    cout.setf(ios_base::fixed);
    cout.precision(28);
    int q;
    cin >> q;
    for (int t = 0; t < q; ++t) {
        int n;
        cin >> n;
        vector < pair < int, int > > x(n);
        vector < int > xs;
        vector < int > ys;
        for (int i = 0; i < n; ++i) {
            cin >> x[i].first >> x[i].second;
            xs.push_back(x[i].first);
            ys.push_back(x[i].second);
        }
        bool ok = false;
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < n; ++j) {
                for (int ii = 0; ii < n; ++ii) {
                    for (int jj = 0; jj < n; ++jj) {
                        auto a = x.front();
                        auto b = x.front();
                        a.first = xs[i];
                        a.second = ys[j];
                        b.first = xs[ii];
                        b.second = ys[jj];
                        //if (a == b)
                        if (rect(a, b, x)) {
                            ok = true;
                        }
                    }
                }
            }
        }
        if (ok) {
            cout << "YES";
        } else {
            cout << "NO";
        }
        cout << endl;
    }
    return 0;
}