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

bool IsPointsValidRect(vector<pair<int, int>> &points)
{
    int minX = points[0].first;
    int maxX = points[0].first;
    int minY = points[0].second;
    int maxY = points[0].second;
    
    for(int i = 0; i < points.size(); i++)
    {
        minX = min(minX, points[i].first);
        maxX = max(maxX, points[i].first);
        minY = min(minY, points[i].second);
        maxY = max(maxY, points[i].second);
    }
    
    for(int i = 0; i < points.size(); i++)
    {
        int x = points[i].first;
        int y = points[i].second;
        
        if(x == minX || x == maxX)
        {
            if(y > maxY || y < minY)
            {
                return false;    
            }
        }
        else if(y == minY || y == maxY)
        {
            if(x > maxX || x < minX)
            {
                return false;
            }
        }
        else
        {
            return false;    
        }
    }
    return true;
}


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int queries;
    
    cin >> queries;
    
    for(int i = 0; i < queries; i++)
    {
        int numPoints;
        cin >> numPoints;
        
        vector<pair<int, int>> points;
        
        for(int j = 0; j < numPoints; j++)
        {
                int x,y;
                cin >> x >> y;
                points.push_back(pair<int, int>(x, y));
        }
        if(IsPointsValidRect(points))
           {
               cout << "YES" << endl;
           }
           else
           {
               cout << "NO" << endl;
           }
    }
    
    
    return 0;
}