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

int main() {
    int q;
    cin>>q;
    while(q--){
        int n;
        cin>>n;
        int x[n],y[n];
        int i =0;
        while(i<n){
            cin>>x[i]>>y[i];
        i++;
        }
        int cx = x[0],cy = y[0],flag;
        for(int j =1;j<n;j++){
            if(x[j]==cx||y[j]==cy){
                flag = 1;
            }
            else{
                flag = 0;
            }
        }
        if(flag){
            cout<<"YES\n";
        }
        else{
            cout<<"NO\n";
        }
    }
    return 0;
}