#include <bits/stdc++.h>
using namespace std;
// #include <atcoder/modint>
// using namespace atcoder;
// using mint = modint998244353;
using ll = long long;
#define fix(x) fixed << setprecision(x)
#define rep(i, n) for(int i = 0; i < n; ++i)
#define all(x) (x).begin(),(x).end()
template<class T>bool chmin(T&a, const T&b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool chmax(T&a, const T&b){if(a<b){a=b;return 1;}return 0;}
constexpr ll INFLL = (1LL << 62), MOD = 998244353;
constexpr int INF = (1 << 30);

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int t;
    cin >> t;
    while(t--){
        int n;
        cin >> n;
        int maxb = 0, minb = INF;
        bool ok1 = false, ok2 = false;
        rep(i,n){
            string x,y;
            cin >> x >> y;
            if(x=="a"){
                ok1 = true;
                for(char c:y){
                    if(c=='a') ok2 = true;
                }
                if(!ok2) chmax<int>(maxb, y.size());
            }else{
                bool f = true;
                for(char c:x){
                    if(c=='a') f = false;
                }
                if(f) chmin<int>(minb, x.size());
            }
        }
        cout << ((ok2 || minb<=maxb) ? "Yes\n":"No\n");
    }
    return 0;
}