#include <iostream>
#include <cstdio>
#include <queue>
#include <vector>
using namespace std;

priority_queue<int, vector<int> , greater<int> >coada;

int n;

int main()
{
    freopen("interclasari.in","r",stdin);
    freopen("interclasari.out","w",stdout);
    scanf("%d ",&n);
    for(int i=1;i<=n;i++)
    {
        int k;
        scanf("%d ",&k);
        for(int j=1;j<=k;j++)
        {
            int a;
            scanf("%d ",&a);
            coada.push(a);
        }
    }
    printf("%d\n",coada.size());
    while(!coada.empty())
    {
        printf("%d ",coada.top());
        coada.pop();
    }
    return 0;
}