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


int main() 
{
    int t;
    cin>>t;
    while(t--)
    {
        int a;
        int flag = 1,i=0,j=0;
        cin>>a;
        int x[a],y[a];
        for(i=0;i<a;i++)
        {
            cin>>x[i];
            cin>>y[i];
        }
        
        sort(x,x+a);
        sort(y,y+a);
        
        int p = x[0];
        int q = x[a-1];
        int r = y[0];
        int s = y[a-1];
        
        for(i=0;i<a;i++)
        {
            if( flag == 1)
            {
                if(x[i] >= p && x[i] <= q && y[i] >= r && y[i] <= s)
                {
                    if(x[i] == p || x[i] == q || y[i] == r || y[i] == s)
                    {
                        flag = 1;
                    }
                    else
                    {
                        flag = 0;
                    }
                }
                else
                {
                    flag = 0;
                }    
            }
        }
        if(flag == 1)
        {
            cout<<"YES"<<endl;
        }
        else
        {
            cout<<"NO"<<endl;
        }
        
    }
    return 0;
}