import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;

import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;
import java.util.Queue;
import java.util.StringTokenizer;
import java.util.ArrayList;
import java.util.TreeSet;

public class Main implements Runnable {
	StringTokenizer st;
	BufferedReader in;
	PrintWriter out;
	String s;
	int color[];
	Queue<Integer> Q;
	ArrayList<TreeSet<Character>>[] pr;
	static int POW = 'z' - 'a' + 2;
	int n, m, k;
	int cur = 0;
	TreeSet<Character> states;
	int ok[];
	int color2[];
	int leftsInUse[];
	char lefts[];


	// //////////////////////////////////////////////////////
	public static void main(String[] args) {
		new Thread(new Main()).start();
	}
	@SuppressWarnings("unchecked")
	void supMov(int a) {
		for (int k=0; k<pr[a].size(); k++) {
			Q.addAll((TreeSet)pr[a].get(k));
		}
	}
	public void run() {
		try {
			in = new BufferedReader(new FileReader("useless.in"));
			out = new PrintWriter(new FileWriter("useless.out"));
			solve();
		} catch (Exception e) {
			e.printStackTrace();
			System.exit(9000);
		} finally {
			out.flush();
			out.close();
		}

	}

	String nextToken() throws IOException {
		while (st == null || !st.hasMoreTokens()) {
			st = new StringTokenizer(in.readLine());
		}
		return st.nextToken();
	}

	int nextInt() throws NumberFormatException, IOException {
		return Integer.parseInt(nextToken());
	}

	long nextLong() throws NumberFormatException, IOException {
		return Long.parseLong(nextToken());
	}

	double nextDouble() throws NumberFormatException, IOException {
		return Double.parseDouble(nextToken());
	}

	@SuppressWarnings("unchecked")
	void solve() throws NumberFormatException, IOException {
		n = nextInt();
		pr=new ArrayList[POW];
		ok=new int[POW];
		for (int i=0; i<POW; i++) pr[i]=new ArrayList<TreeSet<Character>>();


		color=new int[POW];
		color2=new int[POW];

		char start = (char) (nextToken().charAt(0)-'A');
		for (int i = 0; i < n; i++) {
			char t = (char) (nextToken().charAt(0)-'A');
			String s = nextToken();
			color2[t]=1;
			if (st.hasMoreTokens()) {
				s = nextToken();
				TreeSet<Character> T= new TreeSet();
				char let[] = s.toCharArray();
				for (char c : let) {
					if ((c>='A')&&(c<='Z'))
					T.add(c);
				}
				pr[t].add(T);
			} else {
				TreeSet<Character> T = new TreeSet();

				T.add('@');
				pr[t].add(T);


			}

		}
		Q=new LinkedList();
		Q.add((int)start);
		color[start]=1;
		while(!Q.isEmpty()) {
			int a= Q.remove();
			if (color[a]!=1){
				supMov(a);
				color[a]=1;
			}
		}
		for (int i=1; i<POW; i++) {
			if ((color[i]==0)&&(color2[i]!=0)) out.print((char)(i+'A'-1)+" ");
		}


	}
}