#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

struct xy {
    int_fast16_t x, y;
};

int main() {
    int_fast16_t q, n;
    int_fast16_t minx, miny, maxx, maxy;
    cin >> q; cin.ignore();
    for (int_fast16_t i = 0; i < q; ++i)
    {
        cin >> n; cin.ignore();
        vector<xy> p(n);
        minx = miny = 20000;
        maxx = maxy = -20000;
        for (int_fast16_t i = 0; i < n; ++i)
        {
            cin >> p[i].x >> p[i].y;
            cin.ignore();
            minx = min(minx, p[i].x);
            maxx = max(maxx, p[i].x);
            miny = min(miny, p[i].y);
            maxy = max(maxy, p[i].y);
            /*if (p[i].x < minx) minx = p[i].x;
            if (p[i].y < miny) miny = p[i].y;
            if (p[i].x > maxx) maxx = p[i].x;
            if (p[i].y > maxy) maxy = p[i].y;*/
        }
        /*cout << minx << endl;
        cout << maxx << endl;
        cout << miny << endl;
        cout << maxy << endl;*/
        bool yes = true;
        for (auto pt : p)
        {
            if (pt.x != minx && pt.x != maxx && pt.y != miny && pt.y != maxy)
            {
                yes = false;
                break;
            }
        }
        //if (minx == maxx || miny == maxy)
        //    cout << "NO" << endl;
        //else
            cout << (yes ? "YES" : "NO") << endl;
    }
    return 0;
}