#include <iostream>
#include <conio.h>
#include <cctype>
#include <string>
#include <vector>

using namespace std;

bool Palindrom(string rijec);
vector <string> Palindromi (string r);
vector <string> recenica_u_rijec (string a);


int main () {

    string r;
    getline(cin,r);
    vector <string> ispis;
    ispis = recenica_u_rijec(r);
    // = Palindromi(r);
    for (int i = 0; i < ispis.size(); i++) cout << ispis[i];

    getch();
    return 0;

}




bool Palindrom(string rijec) {
    string palindrom;
    int velicina = rijec.length();
    for (int i = 0; i < velicina; i++) rijec[i]=tolower(rijec[i]);
    for (int i = velicina; i > 0; i--) palindrom += rijec[i];
    if (palindrom == rijec) return true;
}


vector <string> recenica_u_rijec (string a) {
    int i;
    vector <string> finalnaRecenica;
    while (int(a[i+1]) != 0) {
        string s;
        while ((a[i] >= 'a' && a[i] <= 'z') || (a[i] >= 'A' && a[i] <= 'Z')){
          s+=a[i];
          i++;
        }
        //i--;
        finalnaRecenica.push_back(s);
        while (int(a[i+1]) != 0 || !((a[i] >= 'a' && a[i] <= 'z') || (a[i] >= 'A' && a[i] <= 'Z'))) i++;
    }
    return finalnaRecenica;
}

vector <string> Palindromi (string r) {
    vector <string> finalnaRecenica, recenica;
    int velicina = r.length();
    recenica = recenica_u_rijec (r);
    for(int i = 0; i < velicina; i++) if (Palindrom (recenica[i])) finalnaRecenica.push_back(recenica[i]);
    return finalnaRecenica;
}