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

const int N = 1e4 + 4;
int main() {
    int t;
    cin >> t;
    while(t--){
        int n;
        cin >> n;
        int maxX = -N;
        int maxY = - N;
        int minX = N;
        int minY = N;
        int x[N], y[N];
        for (int i = 0; i < n; ++i){
            cin >> x[i] >> y[i];
            maxX = max(maxX, x[i]);
            maxY = max(maxY, y[i]);
            minX = min(minX, x[i]);
            minY = min(minY, y[i]);
        }
                
        bool valid = true;
        for (int i = 0; i < n; ++i){
            if(!(x[i] == maxX || x[i] == minX || y[i] == maxY || y[i] == minY))
                valid = false;
        }
        if(valid){
            cout << "YES\n";
        }else{
            cout << "NO\n";
        }
    }
    return 0;
}