#include <iostream>
#include <queue>
#include <fstream>
//#include <utility>


using namespace std;

ifstream fin("interclasari.in");
ofstream fout("interclasari.out");


int main()
{
    int k, n, x;
    priority_queue<int, vector<int>, greater<int> > timp;
    fin >> k;
    while (k--){
        fin >> n;
        while (n--){
            fin >> x;
            timp.push(x);
        }
    }
    fout << timp.size() << '\n';
    while (!timp.empty()){
        fout << timp.top() << ' ';
        timp.pop();
    }
    return 0;
}