#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;
    cin >> q;
    for(int i=0; i<q; i++)
    {
        int n, max1 = -10000, max2 = -10000, min1=10000, min2=10000;
        cin >> n;
        int a[n][2];
        for(int j=0; j<n; j++)
        {
            cin >> a[j][1] >> a[j][2];
            
            if(max1 < a[j][1])
                max1 = a[j][1];
            if(max2 < a[j][2])
                max2 = a[j][2];
            
            if(min1 > a[j][1])
                min1 = a[j][1];
            if(min2 > a[j][2])
                min2 = a[j][2];
        }
        //cout << min1 << min2 << max1 << max2 << endl;
        
        int count=0;
        for(int j=0; j<n; j++)
        {
            if(((a[j][1] == min1 || a[j][1] == max1) && (a[j][2] <= max2 && a[j][2] >= min2)) || ((a[j][2] == min2 || a[j][2] == max2) && (a[j][1] >= min1 && a[j][1] <= max1)))
                count++;
        }
        
        if(count==n)
            cout << "YES" << endl;
        else
            cout << "NO" << endl;
    }
    
    return 0;
}