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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    long long int q,x,y;
    cin>>q;
    while(q--){
        int n;
        cin>>n;
        vector<int>a;
        vector<int>b;
        for(int i=0;i<n;i++){
            cin>>x;
            cin>>y;
            a.push_back(x);
            b.push_back(y);
        }
    
    sort(a.begin(),a.end());
    sort(b.begin(),b.end());
    long long int xmin=a[0];
    long long int xmax=a[n-1];
  long long int ymin=b[0];
    long long int ymax=b[n-1];
    int flag=1;
    for(int i=1;i<n;i++){
        if(((a[i]==xmax)||(a[i]==xmin))&&((b[i]<=ymax)&&(b[i]>=ymin))){flag=1;}
        else if(((b[i]==ymax)||(b[i]==ymin))&&((a[i]<=xmax)&&(a[i]>=xmin))){flag=1;}
        else{flag=0;break;}
    }
    if(flag==0)cout<<"NO"<<endl;
        else{cout<<"YES"<<endl;}
    }return 0;
}