import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int t = Integer.parseInt(br.readLine());
		PrintWriter pw = new PrintWriter(System.out);
		for (int z = 0; z < t; z++) {
			int n = Integer.parseInt(br.readLine());
			String[] x = new String[n];
			String[] y = new String[n];
			for (int i = 0; i < n; i++) {
				String[] sa = br.readLine().split(" ");
				x[i] = sa[0];
				y[i] = sa[1];
			}

			boolean flg1 = false;
			boolean flg2 = false;
			String y2 = "";
			String x2 = "c";
			for (int i = 0; i < n; i++) {
				if (x[i].equals("a")) {
					flg1 = true;
					if (y[i].indexOf("a") != -1) {
						flg2 = true;
					} else if (y[i].length() > y2.length()) {
						y2 = y[i];
					}
				} else if (x[i].indexOf("a") == -1 && x[i].compareTo(x2) < 0) {
					x2 = x[i];
				}
			}
			if (!flg1) {
				pw.println("No");
				continue;
			}

			if (flg2) {
				pw.println("Yes");
				continue;
			}

			if (!x2.equals("c") && x2.length() <= y2.length()) {
				pw.println("Yes");
			} else {
				pw.println("No");
			}
		}
		pw.flush();
		br.close();
	}
}