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

int main() {
    int q;
    scanf("%d",&q);
    while(q--)
    {
        int n,i,ans=0,j;
        scanf("%d",&n);
        int x[n],y[n];
        for(i=0;i<n;i++)
            scanf("%d%d",&x[i],&y[i]);
        int x1=x[0],y1=y[0],x2=x[0],y2=y[0];          
        for(i=0;i<n;i++)
        {
            if(x[i]<x1)
                 x1=x[i];
            if(x[i]>x2)
                 x2=x[i];
            if(y[i]<y1)
                 y1=y[i];
            if(y[i]>y2)
                 y2=y[i];            
        }
        for(i=0;i<n;i++)
        {
            if(x[i]==x1)
            {
                 if(y[i]>y2||y[i]<y1)
                 {
                     ans=1;
                     break;
                 }
            }
            else if(x[i]==x2)
            {
                 if(y[i]>y2||y[i]<y1)
                 {
                     ans=1;
                     break;
                 }
            }
            else if(y[i]==y1)
            {
                 if(x[i]>x2||x[i]<x1)
                 {
                     ans=1;
                     break;
                 }
            }
            else if(y[i]==y2)
            {
                 if(x[i]>x2||x[i]<x1)
                 {
                     ans=1;
                     break;
                 }
            }
            else
            {
                ans=1;
                break;
            }
        }
        if(ans==0)
            printf("YES\n");
        else
            printf("NO\n");
        
    }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */    
    return 0;
}