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


int main() {
       int p_x,p_y,i,j,flag,n,q,max_x,max_y,min_x,min_y;
    cin>>q;
    while(q--){
        cin>>n;
         
        int Points[n][2];
        flag=0;
        
        for(i=0;i<n;i++){
             for(j=0;j<2;j++){
                 cin>>Points[i][j];
             }
        }
        if(n<=3){
             cout<<"YES"<<endl;
             continue;
         }
        
        
        max_x=Points[0][0];
        min_x=Points[0][0];
        max_y=Points[0][1];
        min_y=Points[0][1];
        
        for(i=0;i<n;i++){
             if(Points[i][0]>max_x){
                 max_x=Points[i][0];
             }
             if(Points[i][0]<min_x){
                 min_x=Points[i][0];
             }
             if(Points[i][1]>max_y){
                 max_y=Points[i][1];
             }
             if(Points[i][1]<min_y){
                 min_y=Points[i][1];
             }    
        }
        
        for(i=0;i<n;i++){
            p_x=Points[i][0];
            p_y=Points[i][1];
            if(((p_x!=min_x)&&(p_x!=max_x))&&((p_y!=min_y)&&(p_y!=max_y)))
                flag=1;
     }
        if(flag==1)
            cout<<"NO"<<endl;
        else cout<<"YES"<<endl;
        
        
        
        
    }
       
    return 0;
}