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


int main() {
    int x_min,y_min;
    bool x_min_set= false; 
    bool y_min_set=false;
    int x_max, y_max;
    bool x_max_set = false;
    bool y_max_set = false;
    int x,y;
    int n,q;
    cin>>n;
    bool resolved;
    for(int i=0;i<n;i++){
        
        x_min_set= false; 
        y_min_set=false;
        x_max_set = false;
        y_max_set = false;
        resolved = true;
        cin>>q;
        for(int j=0;j<q;j++){
            cin>>x>>y;
            if(!resolved){
                continue;
            }
            if(x_min_set == false){
                x_min = x;
                x_min_set = true;
            }else if(x_max_set == false && x != x_min){
                x_max = x;
                x_max_set = true;
            }
            
            if(y_min_set == false){
                y_min = y;
                y_min_set = true;
            }else if(y_max_set == false && y != y_min){
                y_max = y;
                y_max_set = true;
            }
            
            if(x_min_set && y_min_set && y_min_set && y_max_set){
                if( !(x == x_min || x == x_max) && !(y == y_min || y == y_max)){
                        cout<<"NO"<<endl;
                        resolved = false;
                                    }
            }
            
        }
        if(resolved){
            cout<<"YES"<<endl;
        }
    } 
    return 0;
}