#include <bits/stdc++.h>
using namespace std;
int solve() {
	int N;
	cin >> N;
	std::vector<pair<string, string>> A(N);
	for (auto& [a, b] : A) cin >> a >> b;
	sort(A.begin(), A.end());
	if (A[0].first != "a") {
		puts("No");
		return 0;
	}
	int fl = 0;
	int ml = 0;
	while (fl < N) {
		if (A[fl].first != "a") break;
		bool ha = false;
		for (auto& a : A[fl].second) ha = ha || (a == 'a');
		if (ha) {
			puts("Yes");
			return 0;
		}
		ml = A[fl].second.size();
		fl ++;
	}
	int mmi = 1e9 + 7;
	for (auto& [a, b] : A) {
		bool ha = false;
		for (auto& x : a) ha = ha || (x == 'a');
		if (!ha) mmi = min(mmi, (int)a.size());
	}
	cout << (ml >= mmi ? "Yes" : "No") << endl;
	return 0;
}
int main () {
	int T;
	cin >> T;
	while (T--) solve();
}