#include <bits/stdc++.h>

using namespace std;
ifstream fin("interclasari.in");
ofstream fout("interclasari.out");
priority_queue <int> q;
int main()
{ int n,x,i,j,k;
  fin>>n;
  for(i=1;i<=n;++i)
  {
       fin>>x;
       for(j=1;j<=x;++j)
       { fin>>k;
           q.push(-k);
       }
  }
    fout<<q.size()<<"\n";
    while(q.size())
    { fout<<-q.top()<<" ";
        q.pop();
    }

    return 0;
}