#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define all(x) begin(x), end(x)

template <class T> bool chmin(T& x, T y) {
	return x > y ? (x = y, true) : false;
}
template <class T> bool chmax(T& x, T y) {
	return x < y ? (x = y, true) : false;
}

struct io_setup {
	io_setup() {
		ios::sync_with_stdio(false);
		cin.tie(nullptr);
		cout << fixed << setprecision(15);
	}
} io_setup;

void solve() {
	int n;
	cin >> n;
	vector<string> x(n), y(n);
	rep(i, 0, n) cin >> x[i] >> y[i];
	int mxln = 0;
	rep(i, 0, n) {
		if (x[i] == "a") {
			if (y[i].contains('a')) {
				cout << "Yes\n";
				return;
			}
			chmax(mxln, (int)y[i].size());
		}
	}
	rep(i, 0, n) {
		if (!x[i].contains('a') && x[i].size() <= mxln) {
			cout << "Yes\n";
			return;
		}
	}
	cout << "No\n";
}

int main() {
	int t = 1;
	cin >> t;
	while (t--) solve();
}