#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    
    int q,n,i,j;
    cin>>q;
    while(q--)
        {
        cin>>n;
        int x[n];
        int y[n];
        for(i=0;i<n;i++)
            {
            cin>>x[i]>>y[i];
            
        }
        int xa,ya,xz,yz;
        xa=x[0];
        ya=y[0];
        xz=x[0];
        yz=y[0];
        for(i=1;i<n;i++)
            {
            if(x[i]<xa)
                {
                xa=x[i];
            }
            if(y[i]<ya)
                {
                ya=y[i];
                
            }
            if(x[i]>xz)
                {
                xz=x[i];
            }
            if(y[i]>yz)
                {
                yz=y[i];
            }
        }
        int f=0;
        for(i=0;i<n;i++)
            {
            if(x[i]==xa && y[i]>=ya && y[i]<=yz)
                {
                continue;
            }
            else if(x[i]==xz && y[i]>=ya && y[i]<=yz)
                {
                continue;
            }
            else if(y[i]==ya && x[i]>=xa && x[i]<=xz)
                {
                continue;
            }
            else if(y[i]==yz && x[i]>=xa && x[i]<=xz)
                {
                continue;
            }
            else
                {
                f=1;
                break;
            }
        }
        if(f==0)
            {
            cout<<"YES"<<endl;
        }
        else
            {
            cout<<"NO"<<endl;
        }
    }
    return 0;
}