import java.util.*;
import java.util.stream.Collectors;
public class Main {
static List<String> list = new ArrayList<>();
public static void main(String[] args){
Scanner sc = new Scanner(System.in);
String s = sc.nextLine();
int n = s.length();
boolean[][] dp = new boolean[n][n];
for (int i = 0; i < n; ++i) {
Arrays.fill(dp[i], true);
}
for (int i = n - 1; i >= 0; --i) {
for (int j = i + 1; j < n; ++j) {
dp[i][j] = (s.charAt(i) == s.charAt(j)) && dp[i + 1][j - 1];
}
}
dfs(s,0,dp);
List<String> ans = list.stream().distinct().collect(Collectors.toList());
}
public static void dfs(String s,int i,boolean[][] dp){
if(i == s.length()){
return;
}
for(int j = i;j<s.length();j++){
if(dp[i][j] == true){
list.add(s.substring(i,j+1));
dfs(s,j+1,dp);
}
}
}
}