#include <iostream>
#include <fstream>
#include <string>

int main()
{
    std::ifstream fin("input.txt");
    std::ofstream fout("output.txt");

    std::string word;

    while (fin >> word)
    {
        for (int i = 0; i < word.length() - 1; i++)
        {
            if (word[i] == word[i + 1])
            {
                fout << word << std::endl;
                break;
            }
        }
    }

    fin.close();
    fout.close();

    return 0;
}