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


int main() {
    int q;
    cin>>q;
    while(q--){
        int n;
        cin>>n;
        vector<pair<int,int> >vp;
        int xm=INT_MAX,xM=INT_MIN,ym=INT_MAX,yM=INT_MIN;
        bool flag=1;
        for(int i=0;i<n;i++){
            int x,y;
            cin>>x>>y;
            vp.push_back(make_pair(x,y));
            ym=min(ym,y);yM=max(yM,y);
            xm=min(xm,x);xM=max(xM,x);
        }
        for(int i=0;i<n;i++){
            int x=vp[i].first;
            int y=vp[i].second;
            if((x>=xm && x<=xM && (y==ym || y==yM))){
                //cout<<x<<","<<y<<"pased\n";
                continue;
            }
            else if((y>=ym && y<=yM && (x==xm || x==xM))){
                continue;
            }
            else{
                flag=0;
                break;
            }
        }
        if(flag==1){
            cout<<"YES\n";
        }
        else{
            cout<<"NO\n";
        }
    }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}