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


int main() {
    int q,n;
    cin>>q;
    outerloop:for(int i=0;i<q;i++)
        {
            
        cin>>n;
           int a[n][2];
        int x,y;
        int maxx,maxy,minx,miny;
        cin>>maxx>>maxy;
        minx=maxx;
        miny=maxy;
         a[0][0]=minx;
         a[0][1]=miny;
 
        for(int j=1;j<n;j++)
            {cin>>x>>y;
             a[j][0]=x;
             a[j][1]=y;
             if(x>maxx)
                 {
                 maxx=x;
             }
             if(x<minx)
                 {
                 minx=x;
             }
             if(y>maxy)
                 {
                 maxy=y;
             }
             if(y<miny)
                 {
                 miny=y;
             }
            
        }
       
        int tempp=0;
        for(int i=0;i<n;i++)
            {
            if(a[i][1]>miny && a[i][1]<maxy)
                {
                 if(a[i][0]==minx || a[i][0]==maxx)
                    {
                    
                }
                else
                {
                    cout<<"NO\n";
                    tempp=1;
                    break;
                }
            }
           
        }
        if(tempp==0)
        cout<<"YES\n";
                    
    }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}