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

using namespace std;

int main(int argc, const char *argv[])
{
    if (argc <= 2)
    {
        cerr << "Usage: " << argv[0] << " FILENAME1 FILENAME2 [FILENAME3 [FILENAME4 [...]]\n";
        return -1;
    }
    auto lists = new vector<string> [argc-1];
    for (int i=1; i<argc; i++)
    {
        ifstream file(argv[i]);
        if (!file.good())
        {
            cerr << "Error openening file \"" << argv[i] << "\"\n";
            return -1;
        }
        lists[i-1].clear();
        string line;
        while (getline(file, line))
        {
            int length = line.length();
            if (line[length-1] == '\n')
                length--;
            if (line[length-1] == '\r')
                length--;
            
            lists[i-1].push_back(line.substr(0, length));
        }
    }

    auto current = new int [argc-1];
    for (int i=0; i<argc-1; i++)
        current[i] = 0;

    for (;;)
    {
        for (int i=0; i<argc-1; i++)
        {
            cout << lists[i][current[i]];
            if (i < argc-2)
                cout << ' ';
        }
        cout << endl;

        for (int j=argc-2;;)
        {
            if (++current[j] < lists[j].size())
                break;
            current[j] = 0;
            if (--j < 0)
                return 0;
        }
    }
}