// Meysam Aghighi
// Comments: 
#include <bits/stdc++.h>
using namespace std;

int main() { 
	int q,n,x,y;
	cin >> q;
	while (q--){
		int minx = 100000, maxx = -100000, miny = 100000, maxy = -100000;
		cin >> n;
		int xx[n], yy[n];
		for (int i=0;i<n;i++){
			cin >> x >> y;
			xx[i] = x, yy[i] = y;
			minx = min(minx,x);
			miny = min(miny,y);
			maxx = max(maxx,x);
			maxy = max(maxy,y);
		}
		bool can = true;
		for (int i=0;i<n;i++){
			if (xx[i]!=minx && xx[i]!=maxx && yy[i]!=miny && yy[i]!=maxy) can = false;
		}
		if (can) cout << "YES" << endl;
		else cout << "NO" << endl;
	}
    return 0;
}