///#include "iostream"
#include <fstream>
#include <queue>
#include "vector"

using namespace std ;

ifstream cin ("interclasari.in") ;
ofstream cout ("interclasari.out") ;

int t, n ;
priority_queue < int, vector < int >, greater < > > PQ ;

int main ()
{

    int x ;

    cin >> t ;

    for (int tt = 0; tt < t; ++tt) {
        cin >> n ;

        for (int i = 0; i < n; ++i) {


            cin >> x ;

            PQ.push(x) ;

        }

    }

    cout << PQ.size() << '\n' ;

    while (!PQ.empty())
        cout << PQ.top() << ' ', PQ.pop();


    return 0 ;

}