#include "bits/stdc++.h"
#define wsp                cin >> ws;
#define sp                 setprecision
#define sz                 size()            
#define sn(n)              scanf("%lld",&n)
#define cn(n)              cin>>n
#define pr(n)              printf("%lld\n",n)
#define ff                 first
#define ss                 second
#define prn                cout<<endl
#define str(n)             scanf("%s",n)
#define pb                 push_back
#define len(n)             n.length()
#define forp(i,a,b)        for(ll i=a;i<=b;i++)
#define rep(i,n)           forp(i,0,n-1)
#define forn(i,a,b)        for(ll i=a;i>=b;i--)
#define ren(i,n)           forn(i,n-1,0)
#define LALIT              ios_base::sync_with_stdio(false);cin.tie(0)
#define tr(container, it)  for(__typeof(container.begin()) it = container.begin(); it != container.end(); it++)
#define mem(n,m)           memset(n,m,sizeof(n))
#define mp                 make_pair
#define mod                1000000007                                                                             

using namespace std;
typedef unsigned long long int ull;
typedef long long int          ll;
typedef pair<int, int>         i_i;
typedef pair<ll, int>          ll_i;
typedef pair<double, int>      d_i;
typedef pair<ll, ll>           ll_ll;
typedef pair<double, double>   d_d;
const int  N = int(300000)+5;
 
template<typename T,typename T1>
void prin(vector<pair<T,T1> >& a)
{
    for(int i=0;i<a.size();i++)
    {
        cout << a[i].fi<<" "<<a[i].se<<"\n";
    }
}
 
 
 
template<typename T>
void prin_new_line(vector<T>& a)
{
    for(int i=0;i<a.size();i++)
    {
        cout << a[i]<<"\n";
    }
}
 
template<typename T,typename T1>
void prin_new_line(vector<pair<T,T1> >& a)
{
    for(int i=0;i<a.size();i++)
    {
        cout << a[i].fi<<" "<<a[i].se<<"\n";
    }
}
 
int sum_vec(vector<int>& a)
{
    int s=0;
    for(int i=0;i<a.size();i++)
    {
        s+=a[i];
    }
    return s;
}
 
template<typename T>
T max(vector<T>& a)
{
    T ans=a[0];
    for(ll i=1;i<a.size();i++)
    {
        ans=max(ans,a[i]);
    }
    return ans;
}
 
template<typename T>
T min(vector<T>& a)
{
    T ans=a[0];
    for(ll i=1;i<a.size();i++)
    {
        ans=min(ans,a[i]);
    }
    return ans;
}
 
template<typename T>
T min(T a,T b,T c)
{
    return min(a,min(b,c));
}
 
template<typename T>
T max(T a,T b,T c)
{
    return max(a,max(b,c));
}
 
long double s_triangle(long double x1,long double y1,long double x2,long double y2,long double x3,long double y3)
{
    return abs(((x2-x1)*(y3-y1)-(x3-x1)*(y2-y1))/2);
}
 
bool overflow(ll a,ll b)
{
    if(a*b/b!=a)
        return true;
    return false;
}

ll n ,   q  , r , ans , sum , mx ;

ll l  , cnt , t ;

ll  a[N] , b[N] , vis[N] ,level[N] ;
/*
    multimap<ll,int> h;
    bool prime[100001];
 
void se()
{
 
  mem(prime,true);
    prime[1]=false;
    for (int p=2; p<=sqrt(100000); p++)
    {
            h.insert(mp(p,p));
            for (int i=p*2; i<=100000; i += p){
                prime[i] = false;
                 h.insert(mp(i,p));
            }
             
    }
 
 
}
*/
int main()
{
	LALIT;
	cin >> t ;
	while(t--)
	{
	cin >> n ;
        ll x[n+1],y[n+1];
	ll mx=-1e18,my=-1e18,ml=1e18,mi=1e18,s1=1e18,f=0;
	rep(i,n)
	{
		cin >> x[i] >> y[i] ;
		mx=max(x[i],mx);
		mi=min(mi,x[i]);
		my=max(y[i],my);
		ml=min(y[i],ml);
	}
	 rep(i,n)
	 {
	 	if(y[i]!=ml and y[i]!=my)
	 	{
	 		if(mx!=x[i] and mi!=x[i])
	 		{
	 			f=1;
	 			break;
			 }
		 }
		 if(x[i]!=mx and x[i]!=mi)
	 	{
	 		if(my!=y[i] and ml!=y[i])
	 		{
	 			f=1;
	 			break;
			 }
		 }
	  }
	 
	  if(f)
	  {
	  	cout <<"NO"<<endl;
	   } 
	   else cout<<"YES"<<endl;
    }
	return 0 ;
}