#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define ll long long
const long long mod=998244353;
const long long hmod=46216567629137;
int main(){
    cin.tie(0)->sync_with_stdio(0);
    cout.tie(0);
    int T;
    cin>>T;
    for(int z=1;z<=T;z++){
        int N;
        cin>>N;
        string X[N+1],Y[N+1];
        for(int i=1;i<=N;i++) cin>>X[i]>>Y[i];
        bool check=0;
        vector<string>nex;
        for(int i=1;i<=N;i++){
            if(X[i]=="a"){
                check=1;
                nex.push_back(Y[i]);
            }
        }
        if(!check){//"a"がないならNO
            cout<<"No\n";
            continue;
        }
        int max_siz=0;
        check=0;
        rep(i,nex.size()){
            bool a=0;
            rep(j,nex[i].size()){
                if(nex[i][j]=='a') a=1;
            }
            if(a) check=1;
            max_siz=max(max_siz,(int)(nex[i].size()));
        }
        if(check){//a->aaなどならyes
            cout<<"Yes\n";
            continue;
        }
        int min_siz=1e9;
        for(int i=1;i<=N;i++){
            bool a=0;
            rep(j,X[i].size()){
                if(X[i][j]=='a') a=1;
            }
            if(!a){
                min_siz=min(min_siz,(int)(X[i].size()));
            }
        }
        if(min_siz<=max_siz){
            cout<<"Yes\n";
        }
        else cout<<"No\n";
    }
}