#include <stdio.h>
#include <vector>
#include <algorithm>
using namespace std;
int K, N;
vector<int> v,SOL,aux;

int main()
{
    freopen("interclasari.in", "r", stdin);
    freopen("interclasari.out","w", stdout);
    scanf("%d", &K);
    for(int i = 0;i<K;i++)
    {
        scanf("%d\n", &N);
        if(N)
        {
            v.resize(N);
            char tmp[2900099];
            fgets(tmp,2900000, stdin);
            char *p =tmp;
            for (int j=0; j<N; j++)
            {
                int val = 0;
                for (; '0' <= *p && *p <= '9'; p++)val = val * 10 + *p - '0';
                for (; '0' > *p || *p > '9'; p++);
                v[j]=val;
            }
            aux.resize(SOL.size() + N);
            merge(v.begin(), v.end(), SOL.begin(), SOL.end(), aux.begin());
            SOL.resize(SOL.size() + N);
            copy(aux.begin(), aux.end(), SOL.begin());
        }
    }
    printf("%d\n", (int)SOL.size());
    for(int i=0;i<SOL.size();i++)printf("%d ", SOL[i]);
    return 0;
}