#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 h,t;
    cin>>t;
    for(h=0;h<t;h++)
    {
        int i,j=0,n;
        cin>>n;
        int x[n],y[n],a[n],b[n];
        for(i=0;i<n;i++)
        {
            cin>>x[i]>>y[i];
            a[i]=x[i];
            b[i]=y[i];
        }
        sort(a,a+n);
        sort(b,b+n);
        
        for(i=0;i<n;i++)
            {
            if(x[i]!=a[0] && x[i]!=a[n-1] && y[i]!=b[0] && y[i]!=b[n-1])
                {j=1;cout<<"NO";break;}
        }
        if(j!=1)
            cout<<"YES";


            cout<<endl;
    }
    return 0;
}