/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

#include <iostream>

using namespace std;

int main(){
    int q;
    cin>>q;
    for(int a=0;a<q;a++){
        int n;
        cin>>n;
        int x[n];
        int y[n];
        int xMax,xMin,yMax,yMin;
        for(int b=0;b<n;b++){
            cin>>x[b];
            cin>>y[b];
            if(b==0){
                xMax=x[0];
                xMin=x[0];
                yMax=y[0];
                yMin=y[0];
            }
            if(x[b]<xMin) xMin=x[b];
            if(x[b]>xMax) xMax=x[b];
            if(y[b]<yMin) yMin=y[b];
            if(y[b]>yMax) yMax=y[b];  
        }
        
        bool res=true;
        for(int a=0;a<n;a++){
            if(x[a]==xMin || x[a]==xMax)
                continue;
            if(y[a]==yMin || y[a]==yMax)
                continue;
            
            res=false;
            break;
        }
        if(res==false){
            cout<<"NO"<<endl;
            continue;
        }
        cout<<"YES"<<endl;
    }
}