#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int q;
    cin>>q;
    for(int m=0;m<q;m++){
        int n;
        cin>>n;
        int x[n],y[n];
        for(int i=0;i<n;i++){
            cin>>x[i]>>y[i];
        }
        if(n==2)
            cout<<"YES\n";
        else{
            int minx=x[0],miny=y[0],maxx=x[0],maxy=y[0],flag=1;
            for(int i=1;i<n;i++){
                minx=min(minx,x[i]);
                maxx=max(maxx,x[i]);
                maxy=max(maxy,y[i]);
                miny=min(miny,y[i]);
            }
            for(int i=0;i<n;i++){
                if(!(x[i]==minx||x[i]==maxx)){
                    if(!(y[i]==miny||y[i]==maxy)){
                        cout<<"NO\n";
                        flag=0;
                        break;
                    }
                }   
            }
            if(flag)
                cout<<"YES\n";
        }
        
        
        
    }
        
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}