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

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        char[] inputs = sc.next().toCharArray();
        int length = inputs.length;
        for (int i = (length - 1) / 2; i < length; i++) {
            int slen1 = i * 2 + 1;
            if (slen1 >= length) {
                char[] output = new char[slen1];
                boolean enable = true;
                for (int j = 0; j < slen1 / 2 + 1 && enable; j++) {
                    int idx = slen1 - j - 1;
                    enable = (idx >= length || inputs[j] == inputs[idx]);
                    output[j] = inputs[j];
                    output[idx] = inputs[j];
                }
                if (enable) {
                    System.out.println(output);
                    return;
                }
            }
            int slen2 = i * 2 + 2;
            char[] output = new char[slen2];
            boolean enable = true;
            for (int j = 0; j < slen2 / 2 && enable; j++) {
                int idx = slen2 - j - 1;
                enable = (idx >= length || inputs[j] == inputs[idx]);
                output[j] = inputs[j];
                output[idx] = inputs[j];
            }
            if (enable) {
                System.out.println(output);
                return;
            }
        }
    }
}
class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}