#include <fstream>
#include <queue>

using namespace std;

priority_queue <int> q;

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

    int k, L, x, cnt = 0;
    scanf("%d", &k);
    while(k--)
    {
        scanf("%d", &L);
        while(L--)
        {
            scanf("%d", &x);
            q.push(-x);
        }
    }
    printf("%d\n", q.size());
    while(!q.empty())
    {
        printf("%d ", -q.top());
        q.pop();
    }
    return 0;
}