#include<bits/stdc++.h>
using namespace std;
# define ll long long int 
ll arr1[1000001],arr2[1000];
string str;
int main(){
	ios::sync_with_stdio(false);cin.clear();
	ll t,n,i,j,ans=0,count=0,sum=0,k,minm,maxm,flag=0,miny,maxy;
	cin>>t;
	while(t--){
		flag=0;
		cin>>n;
		for(i=0;i<n;i++){
			cin>>arr1[i]>>arr2[i];
	}
	if(n<=3){
		cout<<"YES\n";
	}
	else{
		
	
	miny=100000;
	maxy=-100000;
	minm=arr1[0];
	maxm=arr1[0];
		for(i=1;i<n;i++){
			if(arr1[i]<minm){
				minm=arr1[i];
			}
			if(arr1[i]>maxm){
				maxm=arr1[i];
			}
		}
		for(i=0;i<n;i++){
			if(arr1[i]==minm){
				miny=min(miny,arr2[i]);
				maxy=max(maxy,arr2[i]);
			}
		}
		for(i=0;i<n;i++){
			if(arr1[i]==minm||arr1[i]==maxm){
				if(arr2[i]<miny||arr2[i]>maxy){
					flag=1;
				}
			}
			else{
				if(arr2[i]==maxy||arr2[i]==miny){
					
				}else {
					flag=1;
				}
			}
		}
		if(flag==0)cout<<"YES\n";
		else cout<<"NO\n";
	}
	}
}