package com.codegym.task.task22.task2207;
import java.util.LinkedList;
import java.util.*;
import java.io.*;
/*
Inverted words
*/
public class Solution {
public static List<Pair> result = new LinkedList<>();
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
ArrayList<String> normal = new ArrayList<>();
while(reader.ready()){
String[] strings = (reader.readLine().split("\\s+"));
for(String s : strings){
normal.add(s);
}
}
for(int i = 0; i < normal.size(); i++){
StringBuilder str = new StringBuilder(normal.get(i));
if(normal.get(i).equals(str.reverse())){
Pair p = new Pair();
p.first = normal.get(i);
p.second = str.toString();
}
}
}
public static class Pair {
String first;
String second;
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Pair pair = (Pair) o;
if (first != null ? !first.equals(pair.first) : pair.first != null) return false;
return second != null ? second.equals(pair.second) : pair.second == null;
}
@Override
public int hashCode() {
int result = first != null ? first.hashCode() : 0;
result = 31 * result + (second != null ? second.hashCode() : 0);
return result;
}
@Override
public String toString() {
return first == null && second == null ? "" :
first == null ? second :
second == null ? first :
first.compareTo(second) < 0 ? first + " " + second : second + " " + first;
}
}
}