#include<bits/stdc++.h>
#define boost ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define pb push_back
#define mp make_pair
#define ll long long int
#define M 1000000007
#define PI 3.14159265
using namespace std;
struct point
{
    int x;
    int y;
};

int main() 
{
	boost;
    int n,q,xmin,xmax,ymin,ymax,i;
    cin>>q;
    while(q--)
	{
        cin>>n;
        struct point a[n];
        for(i=0;i<n;++i)
        cin>>a[i].x>>a[i].y;
        xmin=a[0].x;
        xmax=a[0].x;
        ymin=a[0].y;
        ymax=a[0].y;
        bool flag=0;
        for(i=1;i<n;++i)
		{
            if(xmin>a[i].x)
            xmin=a[i].x;
            if(xmax<a[i].x)
            xmax=a[i].x;
            if(ymin>a[i].y)
            ymin=a[i].y;
            if(ymax<a[i].y)
            ymax=a[i].y;
        }
        for(i=0;i<n;++i)
		{
            if((a[i].x==xmin)||(a[i].x==xmax)||(a[i].y==ymin)||(a[i].y==ymax))
            continue;
            else
			{
              flag=1;
              break;
            }
        }
        if(flag==0)
        cout<<"YES"<<endl;
        else
        cout<<"NO"<<endl;
    }
    return 0;
}