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


int main() {
    int n,q;
    cin>>q;
    set <int> a,b;
    while(q--)
        {
        cin>>n;
        int x[n],y[n],i;
        for(i=0 ; i<n ; i++ )
            {
            cin>>x[i]>>y[i];
            a.insert(x[i]);
            b.insert(y[i]);
            }
      /*  if(n==1)
            {
            cout<<"YES\n";
            continue;
            }*/
        //if(x[0]==x[1] || y[0]==y[1])
        if(a.size()<=2 && b.size()<=2)
            cout<<"YES\n";
        else
            cout<<"NO\n";
        }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}