#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 q,n;
    cin >> q;
    for(;q>0;q--){
        cin >> n;
        long num[n][2];
        long num1[n],num2[n];
        for(long i=0;i<n;i++){
            cin >> num[i][0] >> num[i][1];
            num1[i]=num[i][0];
            num2[i]=num[i][1];
        }
        sort(num1,num1+n);
        sort(num2,num2+n);
        //cout << num1[n-1] <<" "<< num1[0] <<" "<<num2[n-1]<<" "<<num2[0]<<" ";
        //int maxx=num1[n-1];
        //int maxy=num2[n-1];
        for(long i=0;i<n;i++){
            if(!((num[i][0]==num1[0])||(num[i][0]==num1[n-1])||(num[i][1]==num2[0])||(num[i][1]==num2[n-1]))){
                cout << "NO\n";
                goto LOL;
            }
        }
        cout << "YES\n";
        LOL : continue;
    }
    return 0;
}