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


int main() {
    long long int t;
    cin>>t;
    while(t--)
        {
        long long int var;
        cin>>var;long long x,y,x1,y1,count=0,v;
            cin>>x1>>y1;
        v=var;
        while(var!=1)
            {
            cin>>x;
            cin>>y;
            if(x==x1 || y ==y1)
                count++;
            //long long x,y;
            
            var--;
        }
        if(count == v-1)
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
    }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}