#include <bits/stdc++.h>

using namespace std;

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

int main()
{
    int n;
    in >> n;

    priority_queue<int, vector<int>, greater<int>>pq;

    while (n--)
    {
        int m;
        in >> m;

        for (int i=1; i<=m; i++)
        {
            int x;
            in >> x;
            pq.push(x);
        }
    }

    out << pq.size() << '\n';
    while (!pq.empty())
        out << pq.top() << ' ', pq.pop();

    return 0;
}