import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;

/**
 * Created by camp on 11/26/2014.
 */
public class TaskB {

    BufferedReader reader;
    StringTokenizer tokenizer;
    PrintWriter writer;

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

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

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

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

    public static void main(String[] args) throws IOException {
        new TaskB().run();
    }

    public void solve() throws IOException {
        int n = nextInt();
        TreeMap<String, HashSet<String>> map = new TreeMap<String, HashSet<String>>();
        for (int i = 0; i < n; i++) {
            String s1 = nextToken();
            StringBuilder s2 = new StringBuilder();
            while (tokenizer.hasMoreTokens()) {
                s2.append(nextToken()).append(" ");
            }
            s2.deleteCharAt(s2.length() - 1);
            if (map.containsKey(s1)) {
                map.get(s1).add(s2.toString());
            } else {
                map.put(s1, new HashSet<String>());
                map.get(s1).add(s2.toString());
            }
        }

        boolean[] finished = new boolean[120];
        StringBuilder builder = new StringBuilder();
        int s = map.size();
        String lastS1 = "A";
        for (int i = 0; i < s; i++) {
            Map.Entry<String, HashSet<String>> e = map.firstEntry();
            for (char c : lastS1.toCharArray()) {
                if (!e.getKey().contains(String.valueOf(c))) {
                    finished[c] = true;
                }
            }
            for (char c : e.getKey().toCharArray()) {
                if (finished[c]) {
                    writer.println("Impossible");
                    return;
                }
            }
//            if (e.getKey().equals(lastS1) || (Character.valueOf(e.getKey().charAt(0)).compareTo(lastS1.charAt(lastS1.length() - 1)) >= 0)) {
                for (String s2 : e.getValue()) {

                    builder.append(e.getKey()).append(" ").append(s2).append("\n");

                }
                lastS1 = e.getKey();
//            } else {
//                writer.println("Impossible");
//                return;
//            }
            map.remove(e.getKey(), e.getValue());
        }

        writer.println(builder.toString());
    }

    public void run() {
        try {
            reader = new BufferedReader(new FileReader("b.in"));
            writer = new PrintWriter("b.out");

            solve();

            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

}