#include <bits/stdc++.h>

using namespace std;
ifstream fin("interclasari.in");
ofstream fout("interclasari.out");
int query;
priority_queue<int>c;
int main()
{
    int n;
    fin>>query;
    while(query--)
    {
        fin>>n;
        for(int i=1;i<=n;i++)
        {
            int x;
            fin>>x;
            c.push(-x);
        }
    }
    fout<<c.size()<<"\n";
    while(!c.empty())
    {
        int x;
        x=-c.top();
        fout<<x<<" ";
        c.pop();
    }
    return 0;
}