#include <bits/stdc++.h>
using namespace std;

#define IO ios_base::sync_with_stdio(false); cin.tie(0);
#define endl "\n"
#define DBG 666
#define mp make_pair
#define revsort(x,y) sort((x),(x+y));reverse((x),(x+y));

typedef long long ll;

int main(){

	IO;

	int q;
	cin >> q;
	while(q--){

		int n;
		cin >> n;
		int minx, maxx, miny, maxy;
		minx = miny = 10001;
		maxx = maxy = -10001;
		vector< pair<int, int> > v;
		for(int i = 0; i < n; i++){
			int x, y;
			cin >> x >> y;
			minx = min(minx, x);
			miny = min(miny, y);
			maxx = max(maxx, x);
			maxy = max(maxy, y);
			v.push_back(mp(x, y));
		}

		bool good = true;
		for(int i = 0; i < n; i++){

			int x = v[i].first;
			int y = v[i].second;

			if(y == miny){
				if(x < minx || x > maxx){
					good = false;
					break;
				}
			} else if(y == maxy){
				if(x < minx || x > maxx){
					good = false;
					break;
				}
			} else if(x == minx){
				if(y < miny || y > maxy){
					good = false;
					break;
				}
			} else if(x == maxx){
				if(y < miny || y > maxy){
					good = false;
					break;
				}
			} else {
				good = false;
				break;
			}
		}
		if(good){
			cout << "YES\n";
		} else {
			cout << "NO\n";
		}
	}

	return 0;
}