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


int main() {
    int t,n,x,y;
    cin>>t;
    while(t--)
        {
        vector<pair<int,int> > vect;
        int minx=INT_MAX,miny=INT_MAX,maxx=INT_MIN,maxy=INT_MIN;
        cin>>n;
        for(int i=0;i<n;i++)
            {
            cin>>x>>y;
            if(x<=minx)
                {
                minx=x;
            }
            if(y<miny)
                {
                miny=y;
            }
            if(x>maxx)
                {
                maxx=x;
            }
            if(y>maxy)
                {
                maxy=y;
            }
            vect.push_back(make_pair(x,y));
        }
        int flag=1;
        for(int i=0;i<vect.size();i++)
        {
            if(!(vect[i].first==minx||vect[i].second==miny||vect[i].first==maxx||vect[i].second==maxy))
            {
                flag=0;
            }
        }
        
        if(flag==0)
            {
            cout<<"NO"<<endl;
        }
        else
            {
            cout<<"YES"<<endl;
        }
    }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}