#include <iostream>
#include <fstream>
#include <vector>
#include <stack>
#include <chrono>
#include <iomanip>
#include <unordered_map>
#include <unordered_set>
#include <set>
#include <algorithm>
#include <thread>
#include <numeric>
#include <queue>
#include <functional>
#include <cmath>

using namespace std;

#define endl "\n"
#ifndef MAIN_BEGIN
#define START_TIMER(...)
#define TIMESTAMP(...)
#define MAIN_BEGIN int main() { \
    ios::sync_with_stdio(false);
#define RETURN return 0
#define MAIN_END RETURN; }
#define OUTPUT if(false) cout
#endif

MAIN_BEGIN

    int q;
    cin >> q;
    for(int qq=0; qq<q; qq++) {
        int n;
        cin >> n;
        vector<int> x(n);
        vector<int> y(n);
        int min_x;
        int max_x;
        int min_y;
        int max_y;
        for(int i=0; i<n; i++) {
            cin >> x[i] >> y[i];
        }
        min_x = x[0];
        max_x = x[0];
        min_y = y[0];
        max_y = y[0];
        for(int i=0; i<n; i++) {
            min_x = min(min_x, x[i]);
            max_x = max(max_x, x[i]);
            min_y = min(min_y, y[i]);
            max_y = max(max_y, y[i]);
        }
        bool rectangle = true;
        if(min_x != max_x && min_y != max_y) {
            for (int i = 0; i < n; i++) {
                if (x[i] == min_x) {
                    if (y[i] < min_y || y[i] > max_y) rectangle = false;
                } else if (x[i] == max_x) {
                    if (y[i] < min_y || y[i] > max_y) rectangle = false;
                } else if (y[i] == min_y) {
                    if (x[i] < min_x || x[i] > max_x) rectangle = false;
                } else if (y[i] == max_y) {
                    if (x[i] < min_x || x[i] > max_x) rectangle = false;
                } else {
                    rectangle = false;
                }
            }
        }
        cout << (rectangle ? "YES" : "NO") << endl;
    }

MAIN_END