#include <iostream>
#include <fstream>
using namespace std;

ifstream fin("palindromsd.in");
ofstream fout("palindromsd.out");

bool palindrom(int x)
{
    int y = 0, nr=x;
    while(nr!=0)
    {
        y = y*10 + nr%10;
        nr/=10;
    }
    return x==y;
    /* echivalent cu:
    if(x==y)
        return true;
    else
        return false;
    */
}

int main()
{
    int ar[1001],x,j,i=0,a,nr,b,nr1=0;

    while(fin>>x){ar[++i]=x;}
    for(j=1;j<i;j++)
    {
        if(palindrom(ar[j]))
        {
            fout << ar[j] << " ";
            nr1++;
        }
        if(palindrom(ar[i]))
        {
            fout << ar[i] << " ";
            nr1++;
        }
        i--;
    }
    if(i == j && palindrom(ar[i]))
    {
        fout<<ar[i]<<" ";
        nr1++;
    }

    if(!nr1)fout<<"-1";

    return 0;
}