#include <cstdio>
#include <queue>

using namespace std;

int N, K, x;

priority_queue<int> timeline;

int main()
{
    freopen("interclasari.in", "r", stdin);
    freopen("interclasari.out", "w", stdout);

    scanf("%d", &N);

    for(int i = 0; i < N; i++)
    {
        scanf("%d", &K);

        for(int i = 0; i < K; i++)
        {
            scanf("%d", &x);

            timeline.push(-x);
        }
    }

    printf("%d\n", timeline.size());

    while(!timeline.empty())
    {
        printf("%d ", -timeline.top());

        timeline.pop();
    }

    return 0;
}