#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
#include<bits/stdc++.h>
bool comp(pair<int,int>a,pair<int,int>b)
    {
    if(a.second>b.second)return true;
    else return false;
}
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int q;
    cin>>q;
    while(q--)
    {
        int n;
        int x1 = INT_MAX,y1 = INT_MAX,x2= INT_MIN,y2=INT_MIN;
        cin>>n;
        vector<pair<int,int>>arr(n);
        for(int i = 0 ;i<n;i++)
        {
            int a,b;
            cin>>a>>b;
            if(a<x1)x1 = a;
            if(a>x2)x2 = a;
            if(b<y1)y1 = b;
            if(b>y2)y2  = b;
            arr[i].first = a;
            arr[i].second = b;
        }
        if(n<=2)
        {
            cout<<"YES"<<endl;
        }
        else 
        {
          //  cout<<x1<<" "<<x2<<" "<<" "<<y1<<" "<<y2<<endl;
            bool ch = false;
            for(int i = 0;i<n;i++)
            {
                int x = arr[i].first;
                int y = arr[i].second;
                if(!((x==x1||x == x2)&& y>=y1 && y<=y2) && !((y == y1 ||y==y2)&& x>=x1 && x<=x2))
                {
                    //cout<<x<<" "<<y<<endl;
                    cout<<"NO"<<endl;
                    ch = true;
                    break;
                }
            }
            if(!ch)cout<<"YES"<<endl;
        }
    }
    return 0;
}