#include <bits/stdc++.h>

using namespace std;

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

int n, m, x;
priority_queue<int, vector<int>, greater<int>>h;

int main()
{
    fin>>n;
    for(int i=1; i<=n; ++i)
    {
        fin>>m;
        for(int j=1; j<=m; ++j)
        {
            fin>>x;
            h.push(x);
        }
    }
    fout<<h.size()<<"\n";
    while(!h.empty())
    {
        fout<<h.top()<<" ";
        h.pop();
    }
    fout<<"\n";
    return 0;
}