//*************************************
//*   ????                        *
//*   ??????                    *
//*   ?????2011?12?18?        *
//*************************************


int main()
{
	int n, i, j, flag, p;
	char a[1000];
	cin >> a;//?????
	n = strlen(a);//????????
	for(i = 2; i <= n; i ++)//i??????????????
	{
		for(p = 0; p <= n - i; p ++)//p???????????
		{
			flag = 1;//flag???????????
			for(j = p; j < p + i; j ++)//j?????????
			{
				if(a[j] != a[2 * p + i - 1 - j])
				{
					flag = 0;
					break;//????????,flag??0,??????
				}
			}
			if(flag == 1)
			{
				for(j = p; j < p + i; j ++)
					cout << a[j];//???????,????
				cout << endl;
			}
		}
	}
	return 0;
}
