#include<bits/stdc++.h>
using namespace std;
int main(){
	int q;
	cin>>q;
	while(q--){
		int n;
		cin>>n;
		int x[n+1],y[n+1];
		int x1=100000;int x2=-100000,y1=100000,y2=-100000;
		for(int i=1;i<=n;i++)
			cin>>x[i]>>y[i];
		for(int i=1;i<=n;i++){
		if(x[i]<x1)
		x1=x[i];
		if(x[i]>x2)
		x2=x[i];
		if(y[i]<y1)
		y1=y[i];
		if(y[i]>y2)
		y2=y[i];
		}
		int flag=1;
		if(n<=2)
		{
			flag=0;
			cout<<"YES\n";
		}
		
		for(int i=1;i<=n&&flag;i++){
			if(x[i]==x1||x[i]==x2){
				if(not(y[i]>=y1&&y[i]<=y2))
				{
					cout<<"NO\n";
					flag=0;
				}
			}
			else if(y[i]==y1||y[i]==y2){
				if(not(x[i]>=x1&&x[i]<=x2))
				{
					cout<<"NO\n";
					flag=0;
				}
			}
			else{
				cout<<"NO\n";
				flag=0;
			}
		}
		if(flag)
		cout<<"YES\n";
	}
}