#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 t;
    cin>>t;
    while(t--){
        int n;
        cin>>n;
        int ar[n][2];
        int i,j;
        for(i=0;i<n;i++){
            cin>>ar[i][0]>>ar[i][1];
        }
        int c1 = 0,c2 = 0;
        for(i=0;i<n-1;i++){
            if(ar[i][0] != ar[i+1][0]){
                c1++;
            }
            else if(ar[i][1] != ar[i+1][1]){
                c2++;
            }       
        }
        //cout<<c1<<" "<<c2<<endl;
         if(c1 <2 && c2<2)
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
        
    }
    return 0;
}