#include <iostream>
#include <unordered_map>
#include <fstream>
#include <utility>
#include <iomanip>
#include <vector>

using namespace std;

ifstream fin("date.txt");
int i, n = 0, aux = -1;

struct alpha{
    int cuvantNr;
    int predecesor;
    int combinatii;
};

int main()
{
    unordered_map<string, alpha> wordMap;
    string temp;
    vector<string> originalString, lastLetter, firstLetter, maxSolution;

    getline(fin, temp);
    for(i = 0; i < temp.size(); i++)
    {
        if(temp[i] == ' ')
        {
            originalString.push_back(temp.substr(aux + 1, i - aux - 1));
            aux = i;
        }
    }
    originalString.push_back(temp.substr(aux + 1, temp.size() - aux - 1));
    n = originalString.size();
    for(i = 0; i < n; i++)
    {
        int wordSize = originalString[i].size();
        firstLetter.push_back(originalString[i].substr(0, 2));
        lastLetter.push_back(originalString[i].substr(wordSize - 2, 2));
        alpha aux;
        aux.cuvantNr = i;
        aux.combinatii = 0;
        wordMap.insert(pair<string, alpha>(lastLetter[i], aux));
    }


     for(i = n - 1; i >= 0; i--)
    {
        auto it_ = wordMap.find(lastLetter[i]);
        auto it = wordMap.find(firstLetter[i]);
        if(it != wordMap.end())
        {
            if(i > it -> second.cuvantNr)
            {
                if(it_ -> second.combinatii == 0)
                    it_ -> second.combinatii = 1;
                it -> second.combinatii = it_ -> second.combinatii + 1;
                //cout << it -> second.combinatii << " ";
                it -> second.predecesor = i;
            }
        }
    }
    //cout << endl;
    int maxValue = 0;
    int lookUpValue = 0;
    int predecesor_ = 0;
    unordered_map<string, alpha>::iterator it;
    for(it = wordMap.begin(); it != wordMap.end(); it++)
    {
        //cout <<it -> first <<":"<<it -> second.combinatii << endl ;
        if(maxValue < it -> second.combinatii)
        {
            maxValue = it -> second.combinatii;
            lookUpValue = it -> second.cuvantNr;
            predecesor_ = it -> second.predecesor;

        }
    }
    //cout << endl;
    //cout << maxValue << endl;
    cout << originalString[lookUpValue] << " ";
    cout << originalString[predecesor_] << " ";
    maxValue -= 2;

    while(maxValue)
    {
        auto it = wordMap.find(lastLetter[predecesor_]);

        if(it != wordMap.end())
        {
            maxValue --;
            predecesor_ = it -> second.predecesor;
            cout << originalString[predecesor_] << " ";
        }

    }
    fin.close();
    return 0;
}