#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,x,y,n;
    cin>>q;
    while(q--)
    {
        int flag=0;
        cin>>n;
        vector<pair<int,int> >a,b;
        for(int i=0;i<n;i++)
        {
            cin>>x>>y;
            a.push_back(pair<int,int>(x,y));
            b.push_back(pair<int,int>(y,x));
        }
            sort(a.begin(),a.end());
            sort(b.begin(),b.end());
            int minx=a[0].first;
            //int minxy=a[0].second;
            int maxx=a[n-1].first;
            //int maxxy=a[n-1].second;
            int miny=b[0].first;
            //int minyx=b[0].second;
            int maxy=b[n-1].first;
            //int maxyx=b[n-1].second;
        //cout<<minx<<" "<<miny<<" "<<maxx<<" "<<maxy<<endl;
            for(int i=0;i<n;i++)
            {
                int X=a[i].first;
                int Y=a[i].second;
                if((!(X==minx||X==maxx)) && (!(Y==miny||Y==maxy)))
                {
                    cout<<"NO"<<endl;
                    flag=1;
                    break;
                }
            }
        
        if(flag==0)
            cout<<"YES"<<endl;
    }
    return 0;
}