//**********************************************
//**???????******************************
//**?????? 1000012741*********************
//**???2010?11?26?************************
//**********************************************
void palin ( char str[], int m)                             //??palin????????????????????str???????m?????
{
	int i, j, p;                                            //??i??????j?p??????
	for (i = 0; str[i+1] != '\0'; i++)                      //??????????
	{
			if ( m % 2 == 0 )                               //?????????
			{
				j = i;                                      //?????????
				p = i + 1;
			}
			else                                            //?????????
			{
				j = i - 1;                                  //?????????
				p = i + 1;
			}
			while ( str[j] == str[p] && j >= 0 && str[p] != '\0' )  //???????
			{
				j--;                                        //???????????????
				p++;
				if ( p != (i+1) && ( ( p - j - 1 ) == m ) )         //?????????????
				{
					for ( int k = j + 1; k < p; k++)        //?????
						cout << str[k];
					cout << endl;
				}
			}		
	}
	return;                                                 //palin????
}
int main()                                                  //?????
{
	char str[503];                                          //?????str
	int m, l;                                               //??m????????l????????
	cin >> str;                                             //?????
	l = strlen(str);                                        //???????
	for ( m = 2; m <= l; m = m + 1 )                        //???????????
	{
		palin (str, m);                                     //??palin??
	}	
	return 0;                                               //?????
}
//**********************************************

