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


int main() {
    int q;
    cin>>q;
    while(q--){
        int n;
        cin>>n;
        vector<int> x,y;
        bool result=true;
        int minx=10001,miny=10001,maxx=-10001,maxy=-10001;
        for(int i=0;i<n;i++){
            int a,b;
            cin>>a>>b;
            if(a<minx)
                minx=a;
            if(a>maxx)
                maxx=a;
            if(b<miny)
                miny=b;
            if(b>maxy)
                maxy=b;
            x.push_back(a);
            y.push_back(b);
        }
        for(int i=0;i<n;i++){
            if((x[i]==minx || x[i]==maxx) && (y[i]>=miny && y[i]<=maxy));
            else if((x[i]>=minx && x[i]<=maxx) && (y[i]==miny || y[i]==maxy));
            else{
                result = false;
                break;
            }
        }
        if(result)
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
    }
    return 0;
}