#include <bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int T; cin >> T;
    while(T--){
        int N; cin >> N;
        int needb = 1001001001,maxb = 0;
        bool ok = false;
        while(N--){
            string s,t; cin >> s >> t;
            if(s == "a"){
                int bs = 0;
                for(auto c : t) bs += c=='b';
                if(bs == t.size()) maxb = max(maxb,(int)t.size());
                else ok = true;
            }
            else{
                int bs = 0;
                for(auto c : s) bs += c=='b';
                if(bs == s.size()) needb = min(needb,(int)s.size());
            }
        }
        if(maxb >= needb) ok = true;
        if(ok) cout << "Yes\n";
        else cout << "No\n";
    }
}