#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 */ 
    long q,n,minx,miny,maxx,maxy,a[1000],b[1000],i,flag;
    cin>>q;
    while(q--)
    {
        cin>>n;
        minx=10000;
        miny=10000;
        maxx=-10000;
        maxy=-10000;
        for(i=0;i<n;i++)
        {
            cin>>a[i]>>b[i];
            if(a[i]>maxx)
                maxx=a[i];
            if(a[i]<minx)
                minx=a[i];
            if(b[i]>maxy)
                maxy=b[i];
            if(b[i]<miny)
                miny=b[i];
        }
        flag=0;
        for(i=0;i<n;i++)
        {
            if(a[i]!=minx && a[i]!=maxx &&b[i]!=miny && b[i]!=maxy)
            {
                flag=1;
                break;
            }    
        }
        if(flag==1)
            cout<<"NO"<<endl;
        else cout<<"YES"<<endl;
    }    
    return 0;
}