#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;

#define rep(i,n) for(ll i=0;i<n;++i)
#define all(a) (a).begin(),(a).end()
ll intpow(ll a, ll b){ ll ans = 1; while(b){ if(b & 1) ans *= a; a *= a; b /= 2; } return ans; }
ll modpow(ll a, ll b, ll p){ ll ans = 1; while(b){ if(b & 1) (ans *= a) %= p; (a *= a) %= p; b /= 2; } return ans; }
template<class T> T div_floor(T a, T b) { return a / b - ((a ^ b) < 0 && a % b); }
template<class T> T div_ceil(T a, T b) { return a / b + ((a ^ b) > 0 && a % b); }
template <typename T, typename U> inline bool chmin(T &x, U y) { return (y < x) ? (x = y, true) : false; }
template <typename T, typename U> inline bool chmax(T &x, U y) { return (x < y) ? (x = y, true) : false; }


void solve() {
    ll N;
    cin>>N;
    ll ok_a=0;
    ll ok_b=1e9;
    bool flag=false;
    rep(i,N){
        string x,y;
        cin>>x>>y;
        if (count(all(x),'a')==0){
            chmin(ok_b,x.size());
        }
        else if (x=="a"){
            if (count(all(y),'a')>0){
                flag=true;
            }
            chmax(ok_a,y.size());
        }
    }
    if (flag){
        cout<<"Yes"<<endl;
        return;
    }
    if (ok_a>=ok_b){
        cout<<"Yes"<<endl;
    }
    else{
        cout<<"No"<<endl;
    }
    return;
}


int main() {
    ll T=1;
    cin>>T;
    while (T--){
        solve();
    }
    return 0;
}