#include <bits/stdc++.h>
using namespace std;
// AC verdicts
int main(){
	// freopen("/home/prabhu/Desktop/input.txt","r",stdin);
	// freopen("/home/prabhu/Desktop/output.txt","w",stdout);	
	int q;
    cin>>q;
    while(q--){
        int n;
        cin>>n;
        vector< pair<int ,int > >v;
        int x1=INT_MAX,x2=INT_MIN,y1=INT_MAX,y2=INT_MIN;
       	while(n--){
       		int a,b;
       		cin>>a>>b;
       		v.push_back(make_pair(a,b));
       		x1=min(x1,a);
       		x2=max(x2,a);
       		y1=min(y1,b);
       		y2=max(y2,b);		
       }
       bool ok=1;
       for (int i = 0; i < v.size(); ++i)
       {
       		if((v[i].first==x1 or v[i].first==x2) or (v[i].second==y1 or v[i].second==y2)){
       			ok=ok;
       		}else{
       				ok=0;
       				break;
       			}
       }
       if(ok)
       	cout<<"YES"<<endl;
       else
       	cout<<"NO"<<endl;

      // cout<<x1<<" "<<x2<<" "<<y1<<" "<<y2<<endl;
    }
	
	return 0;
}