#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

int main() {
	int q;
	scanf("%d", &q);
	while (q--) {
		int n;
		scanf("%d", &n);

		int xmin = 1e9;
		int xmax = -1e9;
		int ymin = 1e9;
		int ymax = -1e9;

		pair<int, int> points[n];
		for (int i = 0; i < n; i++) {
			int x, y;
			scanf("%d %d", &x, &y);
			points[i] = make_pair(x, y);

			xmin = min(xmin, x);
			xmax = max(xmax, x);

			ymin = min(ymin, y);
			ymax = max(ymax, y);
		}

		pair<int, int> corners[4];
		corners[0] = make_pair(xmin, ymin);
		corners[1] = make_pair(xmin, ymax);
		corners[2] = make_pair(xmax, ymax);
		corners[3] = make_pair(xmax, ymin);

		bool res = true;
		for (int i = 0; i < n; i++) {
			int x = points[i].first;
			int y = points[i].second;

			bool tmp = false;
			for (int k = 0; k < 4; k++) {
				pair<int, int> c1 = corners[k];
				pair<int, int> c2 = corners[(k + 1) % 4];

				if ((x == xmin || x == xmax) && ymin <= y && y <= ymax) tmp = true;
				if ((y == ymin || y == ymax) && xmin <= x && x <= xmax) tmp = true;
			}
			
			res &= tmp;
		}
		printf("%s\n", res ? "YES" : "NO");
	}
	
	return 0;
}