#include <bits/stdc++.h>
using namespace std;
priority_queue<int> q;
ifstream f("interclasari.in");
ofstream g("interclasari.out");
int main()
{
    int m,n,x;
    f>>m;
    while(m--)
    {
        f>>n;
        while(n--)
            f>>x, q.push(-x);
    }
    g<<q.size()<<'\n';
    while(!q.empty())
        g<<-q.top()<<' ', q.pop();
    return 0;
}