/*input
2
3
0 0
0 1
1 0
4
0 0
0 2
2 0
1 1
*/

//__author__= "Ravi Shankar"

#include<bits/stdc++.h>
using namespace std;

/*******usful typedef's *********/

typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> ii;
typedef list<int>li;
typedef list<li>lii;
typedef set<int>si;
typedef set<si>sii;
typedef map<int,int> mi;

/**************some useful macros/preprocessor********/

#define be_fast std::ios::sync_with_stdio(false);std::cin.tie(NULL)
#define print cout <<
#define ict int t;cin>>t;while(t--)
#define loop(a,b,c)   for (int (a)=(b); (a)<(c); ++(a))
#define loopn(a,b,c)  for (int (a)=(b); (a)<=(c); ++(a))
#define loopd(a,b,c)  for (int (a)=(b); (a)>=(c); --(a))
#define ina(a,n)  loop(i,0,n) cin>>a[i];
#define outa(a,n) loop(i,0,n) cout << a[i]<<" "; cout <<endl;
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define inf INT_MAX
#define linf LONG_MAX
#define MOD 1000000007
#define amount 100005

///iterator range

#define all(c) c.begin(), c.end()
///reverse all iterator
#define rall(c) c.rbegin(),c.rend()
#define tr(c,i) for(typeof((c).begin() i = (c).begin(); i != (c).end(); i++))
#define present(c,x) ((c).find(x) != (c).end())
#define cpresent(c,x) (find(all(c),x) != (c).end())

/***************all user defines functions ******************/


/******************main starts here *************************/

int main() {
    be_fast;
    ict{
    	int n;
    	cin>>n;
    	pair<int,int> arr[n];
    	int x1=inf,x2=-100000,y1=inf,y2=-1000000,x,y;
    	loop(i,0,n){
    		cin>>x>>y;
    		if(x>x2){
    			x2=x;
    		}
    		if(x<x1){
    			x1=x;
    		}
    		if(y>y2){
    			y2=y;
    		}
    		if(y<y1){
    			y1=y;
    		}
    		arr[i].first=x;
    		arr[i].second=y;
    	}
    	// cout << x1 << " "<<y1<<endl;
    	// cout << x2 << " "<<y2 <<endl;
    	string ans="YES";
    	// sort(arr,arr+n);
    	for(int i=0;i<n;i++){
    		if(arr[i].first==x1 or arr[i].first==x2 or arr[i].first==y1 or arr[i].first==y2){
    			continue;
    		}
    		if(arr[i].second==x1 or arr[i].second==x2 or arr[i].second==y1 or arr[i].second==y2){
    			continue;
    		}
    		else{
    			ans="NO";
    			break;
    		}
    	}
    	cout << ans <<endl;
    }
}
/*******************main ends here **************************/