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

int main() {
    int t;
    scanf("%d",&t);
    while(t--)
        {
        int n;
        scanf("%d",&n);
        int a[n],b[n],i;
        for(i=0;i<n;i++)
            scanf("%d%d",&a[i],&b[i]);
        
        int max_x=a[0],max_y=b[0],min_x=a[0],min_y=b[0];
        for(i=1;i<n;i++)
            {
            if(a[i]>max_x)
                max_x=a[i];
            if(a[i]<min_x)
                min_x=a[i];
            if(b[i]>max_y)
                max_y=b[i];
            if(b[i]<min_y)
                min_y=b[i];
        }
        int flag=1;
        for(i=0;i<n;i++)
            {
            if(a[i]!=max_x)
               {
                   if(a[i]!=min_x)
                       {
                       if(b[i]!=max_y)
                           {
                           if(b[i]!=min_y)
                               {
                                 flag=0;
                                    printf("NO\n");  
                               }
                       }
                   }
               }
                
        }
        if(flag)
            printf("YES\n");
    }

    /* Enter your code here. Read input from STDIN. Print output to STDOUT */    
    return 0;
}