#include<iostream>
#include<bits/stdc++.h>
using namespace std;
int main()
{
    int q;
    cin>>q;
    int i;
    for(int i=0;i<q;i++)
    {
        int n,t,r;
        cin>>n;
    bool s=true;
  vector<int>x;vector<int>y;    int j,k,l;
    for(j=0;j<n;j++)
        {cin>>t>>r;x.push_back(t);y.push_back(r);}
        if(n==1||n==2)
        {cout<<"YES"<<endl;
    continue;
        }
        int xmn,xmx,ymn,ymx;
        xmx=*max_element(x.begin(),x.end());xmn=*min_element(x.begin(),x.end());
        ymx=*max_element(y.begin(),y.end());ymn=*min_element(y.begin(),y.end());
       // cout<<xmn<<xmx<<ymn<<ymx<<endl;
        bool st=true;

    for(j=0;j<n;j++)
    {
        if(x[j]!=xmn&&x[j]!=xmx&&y[j]!=ymn&&y[j]!=ymx)
            {st=false;break;}
    }
           if(st)
                cout<<"YES"<<endl;
            else
                cout<<"NO"<<endl;
        }
    return 0;
}