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

class Point
{
  public:
    int m_x;
    int m_y;
  public:
    Point( int x, int y )  { m_x = x;  m_y = y; }
};

bool myComp( Point* x, Point* y )
{
    return x->m_x < y->m_x || ( x->m_x == y->m_x && x->m_y < y->m_y );    
}   

bool myComp2( Point* x, Point* y )
{
    return x->m_y < y->m_y || ( x->m_y == y->m_y && x->m_x < y->m_x );    
}   


int main()
{
    int Q;
    cin >> Q;
    for( int query=0 ; query<Q ; ++query )
    {
        vector<Point*> points;
        int n;
        cin >> n;

        for( int i=0 ; i<n ; ++i )
        {
            int a, b;
            cin >> a >> b;
            points.push_back( new Point( a, b ) );
        }
        
        sort( points.begin(), points.end(), myComp );
        int left   = points[0]->m_x;
        int right  = points[n-1]->m_x;
        sort( points.begin(), points.end(), myComp2 );
        int top    = points[n-1]->m_y;
        int bottom = points[0]->m_y;
        
        bool OK = true;
        for( int i=0 ; i<n ; ++i )
        {
            if( points[i]->m_x != left && points[i]->m_x != right &&
                points[i]->m_y != top && points[i]->m_y != bottom ) 
            {
                OK = false;
                cout << "NO" << endl;
                break;
            }
        }
        if( OK )
            cout << "YES" << endl;
        
        points.clear();
    }
    return 0;
}