#include <queue>
#include <fstream>

using namespace std;

priority_queue<int> q;
int k, n;

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