#include <bits/stdc++.h>

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

int k,n,x;
int i,j;
class compar
{
  public:
  bool operator() (const int& x, const int&y) const
  {
    return (x<y);
  }
};
priority_queue<int,std::vector<int>,compar> H;
int main()
{
    fin>>k;
    for(i=1;i<=k;i++)
    {fin>>n;
    for(j=1;j<=n;j++)
    {fin>>x;H.push(x);}
    }
    fout<<H.size()<<'\n';
    while(H.size())
    {
        fout<<H.top()<<' ';
        H.pop();
    }
}