#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#define ll long long int
using namespace std;


int main() {
      ll q , n , a , b , x , y , l , e , f ;
    cin >> q ;
    while(q--){
        cin >> n ;
        l = 0 , e = 0 , f = 0 ;
        while(n--){
            cin >> a >> b ;
            if(a!=0&&e==0){
                e++ ;
                 x = a ;
            }
            if(b!=0&&f==0){
                f++ ;
                y = b ;
            }
            if((a!=0&&a<x)||(a!=0&&a>x)||(b!=0&&b<y)||(b!=0&&b>y))
                l = 42 ;
        }
        if(l==42)
            cout << "NO" << endl ;
        else
            cout << "YES" << endl ;
    }
    return 0;
}