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

const int INF = 1000001;
vector<pair<int, int>> points;

bool calculate() {
	int i, sz = points.size(), x0 = INF, x1 = -INF, y0 = INF, y1 = -INF;

	for (i = 0; i<sz; i++) {
		if (points[i].first < x0)
			x0 = points[i].first;
		if (points[i].first > x1)
			x1 = points[i].first;

		if (points[i].second < y0)
			y0 = points[i].second;
		if (points[i].second > y1)
			y1 = points[i].second;
	}

	for (i = 0; i<sz; i++) {
		if (points[i].first == x0 || points[i].first == x1)
			continue;
		else {
			if (points[i].second == y0 || points[i].second == y1)
				continue;
			return false;
		}
	}

	return true;
}

int main() {
	/* Enter your code here. Read input from STDIN. Print output to STDOUT */
	int q, n, i;
	int x, y;
	cin >> q;

	while (q--) {
		cin >> n;
		points = vector<pair<int, int>>(n);
		for (i = 0; i< n; i++) {
			cin >> x >> y;
			points[i] = pair<int, int>(x, y);
		}
		cout << (calculate() ? "YES" : "NO") << endl;
	}


	return 0;
}