#include <fstream>
#include <queue>
using namespace std;

priority_queue<int> Q;
int n,k;

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

    int i,j;
    int x;

    scanf("%d",&k);
    for (i = 1; i <= k; i++)
    {
        scanf("%d",&n);
        for (j = 1; j <= n; j++)
        {
            scanf("%d",&x);
            Q.push(-x);
        }
    }
    printf("%d\n",Q.size());

    while (!Q.empty())
    {
        printf("%d ",-Q.top());
        Q.pop();
    }

    return 0;
}