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

#define MOD 1000000007
#define pb push_back
#define mp make_pair
#define all(c) (c).begin(),(c).end()
#define sz(a) int((a).size())
#define F first
#define S second

#define rep(i, a, b) for(int i = a; i < b; ++i)
#define per(i, a, b) for(int i = a; i >= b; --i)
#define travel(c,itr) for(__typeof((c).begin()) itr=(c).begin();itr!=(c).end();itr++)
#define INDEX(arr,ind)			(lower_bound(all(arr),ind)-arr.begin())

typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef pair<int,int> pii;
typedef pair<ll,int> pli;
typedef pair<ll,ll> pll;
typedef pair<int, pii> piii;
typedef pair<ll, pll> plll;
typedef vector<pii> vpii;
typedef vector<piii> vpiii;

inline ll powmod(ll x, ll n, ll _mod){ 
  ll res = 1; 
  while (n){
    if (n & 1)res = (res*x) % _mod; 
    x = (x*x) % _mod; 
    n >>= 1;
    }
    return res; 
  }


#define N 100005
int q;
pii pts[100];

int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

// freopen("in.txt","r",stdin);
// freopen("o.txt","w",stdout);

cin>>q;
while(q--){
    int n;
    cin>>n;
    int x1=1e9;
    int y1=1e9;
    int x2=-1e9;
    int y2=-1e9;
    rep(i,0,n){
    	cin>>pts[i].F>>pts[i].S;
    	x1=min(x1,pts[i].F);
    	x2=max(x2,pts[i].F);
    	y1=min(y1,pts[i].S);
    	y2=max(y2,pts[i].S);
    }
    bool ok=true;
    rep(i,0,n){
    	int x=pts[i].F;
    	int y=pts[i].S;
    	if(x==x1 or x==x2){
    		if(y1<=y and y<=y2)continue;
    		else ok=0;
    	}
    	else if(y==y1 or y==y2){
    		if(x1<=x and x<=x2)continue;
    		else ok=0;
    	}
    	else ok=0;
    }
    if(!ok)cout<<"NO\n";
    else cout<<"YES\n";
}

return 0;
}