#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 */   
    int q,n;
    cin >> q;
    while(q--){
        cin >> n;
        vector<pair<int,int> > array(n);
        int minx=1e5,maxx=-1e5,miny=1e5,maxy=-1e5;
        for(int i=0;i<n;i++){
            cin >> array[i].first >> array[i].second;
            minx = min(array[i].first,minx);
            maxx = max(array[i].first,maxx);
            miny = min(array[i].second,miny);
            maxy = max(array[i].second,maxy);
        }
        bool possible = true ;
        for(int i=0;i<n && possible;i++){
           if( array[i].first != minx && array[i].first != maxx && array[i].second != miny && array[i].second != maxy) possible = false; 
        }
        if(possible) cout << "YES\n";
        else cout << "NO\n";

    }
    return 0;
}