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

typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> ii;

#define fill(a,x) memset(a,x,sizeof(a)) 
#define pb push_back
#define sz(x) (int)x.size() 
#define F first
#define S second
#define FOR(i,a,b) for(int i = a; i<=b; ++i)
#define NFOR(i,a,b) for(int i = a; i>=b; --i)
#define fast ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
const ll INF = 1e18;
const int mod = 1e9+7;
const int N = 1e5+10; 

int same(ii a,ii b){
	if(a.F == b.F)return 1;
	if(a.S == b.S)return 1;
	//cout << a.F << " " << a.S << "\n";
	return 0;
}
ii x[100];
int main(){
  fast;
  int q;
  cin >> q;
  while(q--){
  	int n;
  	cin >> n;
  	FOR(i,0,n-1){
  		cin >> x[i].F >> x[i].S;
  	}
  	ii l=x[0],r=x[0],t=x[0],d=x[0];
  	FOR(i,1,n-1){
  		if(x[i].F < l.F)l = x[i];
  		if(x[i].F > r.F)r = x[i];
  		if(x[i].S < d.S)d = x[i];
  		if(x[i].S > t.S)t = x[i];
  	}
  	//cout << l.F << " " << l.S << "\n";
   	int flag = 1;
  	FOR(i,0,n-1){
  		if(!same(l,x[i]) && !same(r,x[i]) && !same(t,x[i]) && !same(d,x[i]) )flag = 0;
  	}
  	if(flag){
  		cout << "YES\n";
  	}
  	else{
  		cout << "NO\n";
  	}
  }
  return 0;
}