#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,n,A[11][2];
    cin>>q;
    while(q--){
        cin>>n;
        for(int i=0;i<n;i++){
            for(int j=0;j<2;j++){
                cin>>A[i][j];
            }
        }
        int flag=0;
        for(int i=0;i<n;i++){
            for(int j=0;j<2;j++){
                if(A[i][1]==A[i+1][0]&&i<n-1){
                    flag=1;
                }
                else{
                    //cout<<"NO"<<endl;
                    flag=0;
                    break;
                }
            }
            if(flag==0){
                break;
            }
        }
        if(flag==1){
            cout<<"YES"<<endl;
        }
        else
            cout<<"NO"<<endl;
            
        
    }
    return 0;
}