哈希表

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

public class Main {
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(System.out);

        String str = br.readLine();
        boolean[] used = new boolean[10];
        int ans = 0;
        for (int i = str.length() - 1; i >= 0; i--) {
            char c = str.charAt(i);
            if (!used[c - '0']) {
                used[c - '0'] = true;
                ans = ans * 10 + c - '0';
            }
        }
        pw.println(ans);

        pw.flush();
        pw.close();
        br.close();
    }
}