#include <stdio.h>
#include <set>
using namespace std;

int k,nk;
multiset<int> heap;

int main()
{
    freopen("interclasari.in","r",stdin);
    freopen("interclasari.out","w",stdout);
    scanf("%d",&k);
    int nr;
    for(int i=1;i<=k;i++) {
        scanf("%d",&nk);
        for(int i=1;i<=nk;i++) {
            scanf("%d",&nr);
            heap.insert(nr);
        }
    }
    printf("%d\n",heap.size());
    while(!heap.empty()) {
        printf("%d ",*heap.begin());
        heap.erase(heap.begin());
    }
    return 0;
}