#include <cstdio>
#include <queue>

using namespace std;

int n, k, a;
priority_queue < int, vector < int >, greater < int > > Heap;

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