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


int main() {
    int q,n,i;
    cin>>q;
    while(q--)
        {
         cin>>n;
        int k[n],l[n],a,b,c,d,f=0;
        a=INT_MIN;b=INT_MAX;c=INT_MIN;d=INT_MAX; 
        for(i=0;i<n;i++)
            {
             cin>>k[i]>>l[i];
             if(k[i]>a)
                 a=k[i];
            if(k[i]<b)
                b=k[i];
            if(l[i]>c)
                c=l[i];
            if(l[i]<d)
                d=l[i];
        }
        //cout<<a<<' '<<b<<' '<<c<<' '<<d<<'\n';
        for(i=0;i<n;i++)
            {
             if((k[i]==a || k[i]==b ) || (l[i]==c || l[i]==d))
                 continue;
            else{
                f=1;
                break;
            }
        }
        if(f==1)
            cout<<"NO\n";
        else
            cout<<"YES\n";
    }
    
    return 0;
}