#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;
    cin>>q;
    while(q--){
        int n,x,y,x1,x2,y1,y2;
        cin>>n;
        bool flag=true;
        if(n==1) {cout<<"NO"<<endl; break;}
        
       
            cin>>x1>>y1;
            cin>>x2>>y2;
        
            if(x1==x2)x2=-100000;
            else if(y1==y2)y2=-100000;
                       
        for(int i=2;i<n;i++){
            cin>>x>>y;
                if(x2<-10000 && x!=x1)x2=x;
                if(y2<-10000 && y!=y1)y2=y;
                
                if((x!=x1 && x!=x2) && (y!=y1 && y!=y2)){flag=false; break;}  
        }
        if(x2<-10000 || y2<-10000 || flag==false)
        {cout<<"NO"<<endl;}
        else
        {cout<<"YES"<<endl;}
    }
    return 0;
}