#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

/* C implementation QuickSort */
#include<stdio.h>
 
// A utility function to swap two elements
void swap(long int* a, long int* b)
{
    long int t = *a;
    *a = *b;
    *b = t;
}
 
/* This function takes last element as pivot, places
   the pivot element at its correct position in sorted
    array, and places all smaller (smaller than pivot)
   to left of pivot and all greater elements to right
   of pivot */
long int partition (long int arr[], long int low, long int high)
{
    long int pivot = arr[high];    // pivot
    long int i = (low - 1);  // Index of smaller element
 
    for (long int j = low; j <= high- 1; j++)
    {
        // If current element is smaller than or
        // equal to pivot
        if (arr[j] <= pivot)
        {
            i++;    // increment index of smaller element
            swap(&arr[i], &arr[j]);
        }
    }
    swap(&arr[i + 1], &arr[high]);
    return (i + 1);
}
 
/* The main function that implements QuickSort
 arr[] --> Array to be sorted,
  low  --> Starting index,
  high  --> Ending index */
void quickSort(long int arr[], long int low,long  int high)
{
    if (low < high)
    {
        /* pi is partitioning index, arr[p] is now
           at right place */
long int pi = partition(arr, low, high);
 
        // Separately sort elements before
        // partition and after partition
        quickSort(arr, low, pi - 1);
        quickSort(arr, pi + 1, high);
    }
}
 

int main() {

    /* Enter your code here. Read input from STDIN. Print output to STDOUT */    
    long int t;
    scanf("%ld",&t);
    while(t>0)
        {
        t--;
        long int n,i,f1=0,f2=0,x1,X1,y1,Y1,res=0;
        scanf("%ld",&n);
        long int *x,*y;
        x=(long int*)malloc(sizeof(long int)*n);
        
        y=(long int*)malloc(sizeof(long int)*n);
       
        for(i=0;i<n;i++)
            {
             scanf("%ld%ld",&x[i],&y[i]);
        }
               quickSort(x,0,n-1);
        x1=x[0];
        X1=x[n-1];
        
               quickSort(y,0,n-1);
        y1=y[0];
        Y1=y[n-1];
        
         for(i=0;i<n;i++)
            {
             if(x[i]==x1 || x[i]==X1)
                 {
                     if(!(y[i]>=y1 && y[i]<=Y1))
                         res=1;
             }
               
                 else if(y[i]==y1 || y[i]==Y1)
                 {
                     if(!(x[i]>=x1 && x[i]<=X1))
                         res=1;
             }
                 else
                     res=1;
                 
         }
        
        
        
        
        
        
        
       
        
        if(res==0)
            printf("YES\n");
        else
           printf("NO\n");
            
    }
    return 0;
}