#include<bits/stdc++.h>

using namespace std;

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

int k;

int main(){
    fin >> k;
    vector<int> rez;
    while(k--){
        int n; fin >> n;
        vector<int> v(n);
        for(int i = 0 ; i < n ; i++) fin >> v[i];
        if(n == 0) continue;
        vector<int> nou;
        int i = 0 , j = 0;
        while(i < rez.size() && j < n){
            if(rez[i] <= v[j]) nou.push_back(rez[i]) , i++;
            else nou.push_back(v[j]) , j++;
        }
        while(i < rez.size()) nou.push_back(rez[i]) , i++;
        while(j < v.size()) nou.push_back(v[j]) , j++;
        rez = nou;
    }
    fout << rez.size() << '\n';
    for(auto i : rez) fout << i <<" ";
}