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


int main() {
	int q;
	cin >> q;
	
	for(int query = 0; query < q; query++) {
		int n;
		cin >> n;
		
		int xmax = -1000000, xmin = 1000000, ymax = -1000000, ymin = 1000000;
		vector<int> x(n), y(n);
		
		for(int i=0;i<n;i++) {
			cin >> x[i] >> y[i];
			xmax = max(xmax, x[i]);
			xmin = min(xmin, x[i]);
			ymax = max(ymax, y[i]);
			ymin = min(ymin, y[i]);
		}
		
		bool valid = true;
		
		for(int i=0;i<n;i++)
			if(x[i] != xmax && x[i] != xmin && y[i] != ymax && y[i] != ymin)
				valid = false;
		
		if(valid)
			cout << "YES\n";
		else
			cout << "NO\n";
	}
	
	return 0;
}