#include<fstream>
#include<string.h>
#include<ctype.h>
#include<iostream>
#include<algorithm>

using namespace std;

int q,n,x,y,k,i,OK;
int xmin, xmax, ymin, ymax;
int coord[100][3];
int main()
{
	cin >> q;
	for (k = 1; k <= q; k++)
	{
		xmax = ymax = -1000000;
		xmin = ymin = 1000000;
		cin >> n;
		for (i = 1; i <= n; i++)
		{
			cin >> x >> y;
			coord[i][1] = x; 
			coord[i][2] = y;
			if (coord[i][1] > xmax)
				xmax = coord[i][1];
			if (coord[i][2] > ymax)
				ymax = coord[i][2];
			if (coord[i][1] < xmin)
				xmin = coord[i][1];
			if (coord[i][2] < ymin)
				ymin = coord[i][2];
		}
		OK = 1;
		for (i = 1; i <= n; i++)
		{
			if (coord[i][1] <= xmax&&coord[i][1] >= xmin && (coord[i][2] == ymin || coord[i][2] == ymax))
				continue;
			if (coord[i][2] <= ymax&&coord[i][2] >= ymin && (coord[i][1] == xmin || coord[i][1] == xmax))
				continue;
			OK = 0;
		}
		if (OK)
			cout << "YES\n";
		else
			cout << "NO\n";
	}
	return 0;
}