#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <bits/stdc++.h>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int t,n,m,i,j,k,maxx,minx,maxy,miny;
    cin >> t;
    while(t--)
        {
        cin >> n;
        vector<int> x;
        vector<int> y;
        for(i=0;i<n;i++)
            {
            cin >> k;
            x.push_back(k);
            cin >> k;
            y.push_back(k);
        }
        minx=*min_element(x.begin(),x.end());
        maxx=*max_element(x.begin(),x.end());
        miny=*min_element(y.begin(),y.end());
        maxy=*max_element(y.begin(),y.end());
        if(n<3)
             cout << "YES\n";
        else
            {
            for(i=0;i<n;i++)
                {
                if(x[i]!=minx && x[i]!=maxx)
                    {
                    if(y[i]!=miny && y[i]!=maxy)
                        {
                        cout << "NO\n";
                        break;
                    }
                }
            }
            if(i==n)
                cout << "YES\n";
        }
    }
    return 0;
}