#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r) - 1;i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
void solve() {
	int n; cin >> n;
	vector<string>x(n), y(n);
	rep(i, n)cin >> x[i] >> y[i];
	int sz = INF;
	bool chk = false;
	rep(i, n)if (x[i] == "a") {
		auto cy = y[i];
		sort(all(cy));
		if (cy[0] == 'a') {
			cout << "Yes" << endl;
			return;
		}
		else chmin(sz, y[i].size());
		chk = true;
	}
	if (!chk) {
		cout << "No" << endl;
		return;
	}
	int sz2 = INF;
	rep(i, n) {
		auto s = x[i];
		for (int j = 0; j < s.size();) {
			if (s[j] == 'a') {
				j++;
				continue;
			}
			int k = j + 1;
			while (k < s.size() && s[k] == 'b')k++;
			chmin(sz2, k - j);
			j = k;
		}
	}
	if (sz2 <= sz)cout << "Yes" << endl;
	else cout << "No" << endl;
}
int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	int t; cin >> t;
	while (t--)solve();
	return 0;
}