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



int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int q,n,xflip,yflip,a,b,i,j;
    int maxa,maxb,mina,minb;
   
    
        cin>>q;
    while(--q>=0)
        {
        cin>>n;
        yflip=xflip=0;
        i=0;j=0;
         int arr[1000];
    int arr1[1000];
        maxb=maxa=INT_MIN;
    mina=minb=INT_MAX;
        while(--n>=0)
            {
            cin>>a>>b;
            if(a>maxa)
                maxa=a;
            if(a<mina)
                mina=a;
            if(b>maxb)
                maxb=b;
            if(b<minb)
                minb=b;
            arr[i++]=a;
            arr1[j++]=b;
                
            }
        for(int ii=0;ii<i;ii++)
            {
            if(arr[ii]==maxa||arr[ii]==mina)
                {
                
            }
            else
                {
                if(arr1[ii]==maxb||arr1[ii]==minb)
                    {
                    
                }
                else
                    {
                    xflip=1;
                    yflip=1;
                    break;
                }
            }
        }
        
       
        
        if(xflip==1 && yflip==1)
            cout<<"NO"<<endl;
        else
            cout<<"YES"<<endl;
    }
    return 0;
}