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


typedef struct POINTS
    {
    int x;
    int y;
}Points;

bool myfunc (Points x ,Points y)
    {
    return x.x<y.x;
}
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int q = 0;
    cin>>q ;
    
    while(q-- > 0)
        {
        int n =0;
        cin >> n; 
        
        Points p[n];
        for(int i=0;i<n;i++)
            {
                cin >> p[i].x >> p[i].y;
            }
        
        int minx=1e6,miny=1e6,maxx=-1e6,maxy=-1e6;
        
        for(int i=0;i<n;i++)
            {
            if( p[i].x<minx)
                {
                minx = p[i].x;
            }
             if( p[i].x>maxx)
                {
                maxx = p[i].x;
            }
                if( p[i].y<miny)
                {
                miny = p[i].y;
            }
             if( p[i].y>maxy)
                {
                maxy = p[i].y;
            }
        }
        
        bool b = false;
        
        for(int i=0;i<n;i++)
            {
            if( p[i].x == minx || p[i].x ==maxx)
                {
                if(p[i].y >=miny && p[i].y <=maxy )
                    {
                    b = true;
                }
                else
                    {
                    b = false;
                    break;
                }
                   
            }
             else if( p[i].y == miny || p[i].y ==maxy)
                {
                if(p[i].x >=minx && p[i].x <=maxx )
                    {
                    b = true;
                }
                else
                    {
                    b = false;
                    break;
                }
                   
            }
            else
                {
                b = false;
                break;
            }
        }
            
        
        
        if(b)cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
        
            
        
    }
    return 0;
}