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

struct P
{
    int x,y;
};

int main() {
    int q;
    cin >> q;
    for (int i = 0; i < q; i++)
    {
        int n;
        cin >> n;
        vector<P> points(n);
        for (int j = 0; j < n; j++)
        {
            cin >> points[j].x >> points[j].y;
        }
        int left = 1000000, right = -1000000, top = -1000000, bottom = 1000000;
        for (int j = 0; j < n; j++)
        {
            left = min(left, points[j].x);
            right = max(right, points[j].x);
            bottom = min(bottom, points[j].y);
            top = max(top, points[j].y);
        }
        bool ok = true;
        for (int j = 0; j < n; j++)
        {
            if (points[j].x != left && points[j].x != right &&
               points[j].y != bottom && points[j].y != top)
            {
                ok = false;
                break;
            }
        }
        cout << (ok ? "YES" : "NO") << endl;
    }
}