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

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
#define rep3(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define rep2(i, a, b) rep3(i, a, b, 1)
#define rep1(i, n) rep2(i, 0, n)
#define rep0(n) rep1(aaaaa, n)
#define ov4(a, b, c, d, name, ...) name
#define rep(...) ov4(__VA_ARGS__, rep3, rep2, rep1, rep0)(__VA_ARGS__)
#define per(i, a, b) for (ll i = (a) - 1; i >= (b); i--)
#define fore(e, v) for (auto&& e : v)
#define all(a) begin(a), end(a)
#define sz(a) (int)(size(a))
#define lb(v, x) (lower_bound(all(v), x) - begin(v))
#define eb emplace_back

template <typename T, typename S>
bool chmin(T& a, const S& b) {
  return a > b ? a = b, 1 : 0;
}
template <typename T, typename S>
bool chmax(T& a, const S& b) {
  return a < b ? a = b, 1 : 0;
}
const int INF = 1e9 + 100;
const ll INFL = 3e18 + 100;
#define i128 __int128_t
struct _ {
  _() { cin.tie(0)->sync_with_stdio(0), cout.tie(0); }
} __;


void solve();

int main(){
  int T;
  cin>>T;
  rep(T)solve();
}

void solve(){
  int N;
  cin>>N;
  bool startA=0,Aloop=0;
  int maxBend=0,minBstart=1e9;
  rep(N){
    string X,Y;
    cin>>X>>Y;
    if(X=="a"){
      startA=1;
      bool allB=1;
      fore(i,Y){
        if(i!='b')allB=0;
      }
      if(allB){
        chmax(maxBend,sz(Y));
      }else{
        Aloop=1;
      }
    }else{
      bool allB=1;
      fore(i,X){
        if(i!='b')allB=0;
      }
      if(allB){
        chmin(minBstart,sz(X));
      }
    }
  }
  if(Aloop||maxBend>=minBstart){
    cout<<"Yes\n";
  }else{
    cout<<"No\n";
  }
}