#include<bits/stdc++.h>
#define rep(i,x,y) for(i=x;i<y;i++)
#define pb(f) push_back(f)
#define ll long long
#define mp make_pair
#define fi first
#define se second
#define mod 1000000007
using namespace std;

//#include<windows.h>
//FILE *fin = freopen("33.in","r",stdin);  FILE *fout = freopen("out.txt","w",stdout);
using namespace std;
typedef pair<ll, ll> pii;
typedef vector<ll > vi;
typedef vector< pii > vpii;

const int N=2e5+5;
ll x[N],y[N];
int main()
{
	int t;
	cin>>t;
	while(t--)
	{
		int n,i,j,k,l;
		cin>>n;
		rep(i,1,n+1) {
			cin>>x[i]>>y[i];
		}
		rep(i,1,n+1)
		{
			int l=0,r=0,u=0,d=0;
			rep(j,1,n+1)
			{
				if(j==i) continue;
				if(x[j]<x[i]) l++;
				if(x[j]>x[i]) r++;
				if(y[j]<y[i]) d++;
				if(y[j]>y[i]) u++;
			}
			if(u&&l&&d&&r) {
				cout<<"NO"<<endl;break;
			}
		}
		if(i==n+1)
		{
			cout<<"YES"<<endl;
		}
	}
}