#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i,s,n) for (int i = (s); i < (n); ++i)
#define rrep(i,n,g) for (int i = (n)-1; i >= (g); --i)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define len(x) (int)(x).size()
#define dup(x,y) (((x)+(y)-1)/(y))
#define pb push_back
#define eb emplace_back
#define Field(T) vector<vector<T>>
using namespace std;
using ll = long long;
using ull = unsigned long long;
template<typename T> using pq = priority_queue<T,vector<T>,greater<T>>;
using P = pair<int,int>;
template<class T>bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T&a,T b){if(b<a){a=b;return 1;}return 0;}

void solve() {
  int n;
  cin >> n;
  vector<string> x(n), y(n);
  rep(i,0,n) cin >> x[i] >> y[i];
  int cnt = -1;
  rep(i,0,n) {
    if (x[i] == "a") {
      int ok = 0;
      for (char c : y[i]) {
        if (c == 'a') ok = 1;
      }
      if (ok) {
        cout << "Yes" << endl;
        return;
      } else {
        cnt = max(cnt, len(y[i]));
      }
    }
  }
  if (cnt == -1) {
    cout << "No" << endl;
    return;
  }
  rep(i,0,n) {
    int cb = 0;
    for (char c : x[i]) cb += (c == 'b');
    if (cb != len(x[i])) continue;
    if (cb <= cnt) {
      cout << "Yes" << endl;
      return;
    }
  }
  cout << "No" << endl;
  return;
}

int main() {
  int t;
  cin >> t;
  while(t--) solve();
  return 0;
}