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


int main() {
    int q;
    std::cin >> q;
    for (int i = 0; i < q; i++)
    {
        int n;
        int minx = 100000;
        int miny = 100000;
        int maxx = -100000;
        int maxy = -100000;
        std::cin >> n;
        std::vector<std::pair<int, int> > points(n);
        for (int j = 0; j < n; j++)
        {
            int x, y;
            std::cin >> x >> y;
            points[j].first = x;
            points[j].second = y;
            minx = std::min(minx, x);
            maxx = std::max(maxx, x);
            miny = std::min(miny, y);
            maxy = std::max(maxy, y);
        }
        //std::cout << minx << miny << maxx << maxy << std::endl;
        // verify
        bool fine = true;
        for (int j = 0; j < n; j++)
        {
            if (!((points[j].first == minx && points[j].second >= miny && points[j].second <= maxy) ||
               (points[j].first == maxx && points[j].second >= miny && points[j].second <= maxy) ||
                 (points[j].second == miny && points[j].first >= minx && points[j].first <= maxx) ||
               (points[j].second == maxy && points[j].first >= minx && points[j].first <= maxx)))
            {
                fine = false;
                break;
            }
        }
        std::cout << (fine? "YES" : "NO") << std::endl;
    }
    return 0;
}