#include<iostream>
using namespace std;
int main(){
int h,t;
cin>>t;
for(h=0;h<t;h++){
int n,a[20],b[20],one=-1,two=-1,i,mini=10001,maxi=-10001;
bool oneb=true,twob=true;
cin>>n;
for(i=0;i<n;i++){
cin>>a[i]>>b[i];
}
for(i=0;i<n;i++){
mini=min(mini,a[i]);
maxi=max(maxi,a[i]);
if(one==-1&&two==-1){
one=a[i];
}
else if(two==-1&&one!=a[i]){
two=a[i];
}
else if(two!=a[i]&&one!=a[i]&&two!=-1&&one!=-1){
oneb=false;
break;
}}
one=-1;
two=-1;
if(oneb==true){
for(i=0;i<n;i++){
if(a[i]<mini||a[i]>maxi)
{twob=false;
break;}
if(one==-1&&two==-1){
one=a[i];
}
else if(two==-1&&one!=a[i]){
two=a[i];
}
else if(two!=a[i]&&one!=a[i]&&two!=-1&&one!=-1){
twob=false;
break;
}
}
}
if(oneb==true&&twob==true){cout<<"YES"<<endl;}
else {cout<<"NO"<<endl;}
}}