#include<bits/stdc++.h>
#define ll long long 
#define pb push_back
#define mp make_pair
#define mod 1000000007
#define fast ios_base::sync_with_stdio(0);cin.tie(0);
#define afor(i,a,b) for(int i=a;i<b;++i)
#define ps cout<<"YES\n";
using namespace std;
int main()
{
	fast
	int t;
	cin>>t;
	while(t--)
	{
		int n,right=-100000,left=100000,top=-100000,down=100000,f=0,a[100000],b[100000];
		cin>>n;
		afor(i,0,n)
		{
			cin>>a[i]>>b[i];
			if(a[i]>right)
				right=a[i];
			if(a[i]<left)
				left=a[i];
			if(b[i]>top)
				top=b[i];
			if(b[i]<down)
				down=b[i];
		}
		//cout<<right<<" "<<left<<" "<<top<<" "<<down<<"\n";
		afor(i,0,n)
		{
			if(a[i]==left || a[i]==right)
			{
				if(b[i]<down || b[i]>top)
				{
					f=1;
					cout<<"NO\n";
					break;
				}
			}
			else if(b[i]==top || b[i]==down)
			{
				if(a[i]<left || a[i]>right)
				{
					f=1;
					cout<<"NO\n";
					break;
				}	
			}
			else
			{
				f=1;
				cout<<"NO\n";
				break;
			}
		}
		if(f==0)
			cout<<"YES\n";
	}
	return 0;
}