//***********************
//???????
//?????? 1200012914
//???2012.11.11
//*********************** 


int main()
{
    char str[501]; //?????\0
    int len; //???????len
    int i, j, k, l; //?????? 
    cin >> str; //????
    len = strlen(str); //????????
    for (i = 2; i <= len; i++) //??????????2????len
    {
        for (j = 0; j <= len - i; j++)
        //????????i??????????????len-i+1?
        //?????len-i???
        {
            for (k = 1; k <= i / 2; k++)
            //?????????????????i/2?????
            {
                if (str[j + k - 1] != str[j + i - k]) break;
                //?????????????????
            }
            if (k == i / 2 + 1) //k=1/2+1???????????????
            {
                  for (l = j; l < j + i; l++) 
                  //????????j????i?????????j+i-1??
                  {
                      cout << str[l];
                  }
                  cout << endl; //????????????
            } 
        } 
    }             

    return 0;
}
    
