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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int q;
    int n;
    
    cin >> q;
    
    for (int query = 0; query < q; query++)  
    {
        cin >> n;   // # of points in the query
        int num = 0;
        int xMin, xMax, yMin, yMax; // Stores the range of values x and y could be
        vector<pair<int, int>> points;   // Vector of size n
        
        while (num < n)
        {
            int x, y;
            cin >> x >> y;  // Grabs the x and the y
            
            if (num == 0)   // The first pair
            {
                xMin = x;
                xMax = x;
                yMin = y;
                yMax = y;
            }
            
            // Re-adjust x range
            if (x < xMin)
                xMin = x;
            else if (x > xMax)
                xMax = x;
            
            // Re-adjust y range
            if (y < xMin)
                yMin = y;
            else if (y > yMax)
                yMax = y;
            
            points.push_back(make_pair(x, y));  // Adds the coordinates to the vector
            num++;
        }

        // Check the points to see if they are part of the rectangle
        int i = 0;
        bool isRect = true;
        
        while (i < n && isRect)
        {
            pair<int, int> point = points.at(i);

            // cout << "Checking point: (" << point.first << ", " << point.second << ")" << endl;
            
            // Check if the x or y coordinate is not equal
            if (point.first != xMin && point.first != xMax && point.second != yMin && point.second != yMax)
            {
                isRect = false;
            }
            i++;
        }

        if (isRect)
            cout << "YES" << endl;
        else
            cout << "NO" << endl;
    }
    
    return 0;
}