#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

bool solve() {
  int n;
  cin >> n;
  vector<pair<string, string>> xy(n);
  for (auto& [x, y] : xy) cin >> x >> y;
  int mx = -1;
  for (auto& [x, y] : xy) if (x == "a") {
    if (count(all(y), 'a')) return true;
    chmax<int>(mx, ssize(y));
  }
  if (mx == -1) return false;
  for (auto& [x, y] : xy) if (!count(all(x), 'a') && ssize(x) <= mx) return true;
  return false;
}

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int tt;
  cin >> tt;
  while (tt--) {
    cout << (solve() ? "Yes\n" : "No\n");
  }
}