#include <cmath>
#include <climits>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <utility>
#define MAX 100010
using namespace std;

pair<int, int> v[MAX];

bool in(int min_x, int max_x, int min_y, int max_y, pair<int, int> p){
    if(min_x <= p.first && p.first <= max_x && (min_y == p.second || max_y == p.second))
        return true;
    if(min_y <= p.second && p.second <= max_y && (min_x == p.first || max_x == p.first))
        return true;
    return false;
}

string solve(int n){
    int min_x = INT_MAX, min_y = INT_MAX, max_x = INT_MIN, max_y = INT_MIN;
    for(int i = 0; i < n; i++){
        min_x = min(min_x, v[i].first);
        max_x = max(max_x, v[i].first);
        min_y = min(min_y, v[i].second);
        max_y = max(max_y, v[i].second);
    }
    for(int i = 0; i < n; i++){
        if(!in(min_x, max_x, min_y, max_y, v[i]))
           return "NO" ;
    }
    return "YES";
}

int main() {
    int n, a, b, cases;
    cin >> cases;
    while(cases--){
        cin >> n;
        for(int i = 0; i < n; i++){
            cin >> v[i].first >> v[i].second;
        }
        cout << solve(n) << endl;
    }
    return 0;
}