#include<iostream>
#include<string.h>
#include<algorithm>
#include<math.h>
#define maxi 12
using namespace std;

struct point{
	int x;
	int y;
};

int main(){
	int q,n;
	cin>>q;
	for(int i=1;i<=q;i++){
		point pt[maxi] = {0};
		int flag = 0;
		cin>>n;
		int max = -10005;
		int may = -10005;
		int mix = 10005;
		int miy = 10005;
		for(int j=0;j<n;j++){
			cin>>pt[j].x>>pt[j].y;
		}
		if(n<=2){
			cout<<"YES"<<endl;
		}
		else{
			for(int j=0;j<n;j++){
				if(max<pt[j].x){
					max = pt[j].x;
				}
				if(may<pt[j].y){
					may = pt[j].y;
				}
				if(mix>pt[j].x){
					mix = pt[j].x;
				}
				if(miy>pt[j].y){
					miy = pt[j].y;
				}				
			}
			
			for(int j=0;j<n;j++){
				if((pt[j].x==max||pt[j].x==mix)&&(pt[j].y>=miy&&pt[j].y<=may)){
					
				}
				else if((pt[j].y==may||pt[j].y==miy)&&(pt[j].x>=mix&&pt[j].x<=max)){
					
				}
				else{
					flag = 1;
					break;
				}
			}
			if(flag==1){
				cout<<"NO"<<endl;
			}
			else{
				cout<<"YES"<<endl;
			}
		}
		
	}
}