#include <fstream>
#include <queue>
using namespace std;
ifstream fin("interclasari.in");
ofstream fout("interclasari.out");
int n, i, a,k;
priority_queue<int,  vector<int> , greater<int> > h;

int main()
{
    fin>>k;
    for(;k>0;k--)
    {
        fin>>n;
        for(i=1;i<=n;i++)
        {
            fin>>a;
            h.push(a);
        }
    }
    fout<<h.size()<<"\n";
    while(h.size())
    {
        fout<<h.top()<<" ";
        h.pop();
    }
    return 0;
}