#include<bits/stdc++.h>
using namespace std;
ifstream fin("interclasari.in");
ofstream fout("interclasari.out");

int k, n;
priority_queue<int, vector<int>, greater<int>> S;

int main()
{
    fin >> k;
    while(k--)
    {
        fin >> n;
        for(int i = 0; i < n; ++i)
        {
            int x;
            fin >> x;
            S.push(x);
        }
    }

    fout << S.size() << '\n';
    while(!S.empty())
    {
        fout << S.top() << ' ';
        S.pop();
    }

    return 0;
}