temp

import java.io.*;
import java.util.*;

public class MaxRepeats {
    FastScanner in;
    PrintWriter out;

    class Answer implements Comparable<Answer> {
        String s;
        int len;

        Answer(String s) {
            this.s = s;
            len = s.length();
        }

        @Override
        public int compareTo(Answer o) {
            return Integer.compare(o.len, len);
        }
    }

    boolean inside(String sub, String in) {
        int len = sub.length();
        for (int st = 0; st < in.length(); st++) {
            if (st + len > in.length())
                continue;
            if (in.substring(st, st + len).equals(sub))
                return true;
        }
        return false;
    }

    ArrayList<String> stupid(String s) {
        ArrayList<String> res = new ArrayList<>();
        int n = s.length();
        for (int st = 0; st < n; st++)
            for (int to = st + 1; to <= n; to++) {
                String substr = s.substring(st, to);
                res.add(substr);
            }
        Collections.sort(res);
        ArrayList<String> repeats = new ArrayList<>();
        for (int i = 1; i < res.size(); i++) {
            String last = repeats.size() == 0 ? "" : repeats
                    .get(repeats.size() - 1);
            if (res.get(i).equals(res.get(i - 1)))
                if (!res.get(i).equals(last))
                    repeats.add(res.get(i));
        }
        ArrayList<Answer> a1 = new ArrayList<Answer>();
        for (String s2 : repeats)
            a1.add(new Answer(s2));
        Collections.sort(a1);
        ArrayList<String> aa = new ArrayList<>();
        for (Answer a : a1) {
            boolean ok = true;
            for (String alr : aa) {
                if (inside(a.s, alr)) {
                    ok = false;
                    break;
                }
            }
            if (ok) {
                aa.add(a.s);
            }
        }
        return aa;
    }

    void solve() {
        //String s = "abacaba";
        String s = "abcdabcabcdaabbcaa";
        ArrayList<String> st = stupid(s);
        for (String s2 : st)
            System.err.println(s2);
    }

    void run() {
        try {
            in = new FastScanner(new File("object.in"));
            out = new PrintWriter(new File("object.out"));

            solve();

            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

    void runIO() {

        in = new FastScanner(System.in);
        out = new PrintWriter(System.out);

        solve();

        out.close();
    }

    class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner(File f) {
            try {
                br = new BufferedReader(new FileReader(f));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }

        public FastScanner(InputStream f) {
            br = new BufferedReader(new InputStreamReader(f));
        }

        String next() {
            while (st == null || !st.hasMoreTokens()) {
                String s = null;
                try {
                    s = br.readLine();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (s == null)
                    return null;
                st = new StringTokenizer(s);
            }
            return st.nextToken();
        }

        boolean hasMoreTokens() {
            while (st == null || !st.hasMoreTokens()) {
                String s = null;
                try {
                    s = br.readLine();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (s == null)
                    return false;
                st = new StringTokenizer(s);
            }
            return true;
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }
    }

    public static void main(String[] args) {
        new MaxRepeats().runIO();
    }
}