#include <iostream>
#include <cstdio>
#include <queue>

using namespace std;

priority_queue <int> q;
int N, t, p;

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

    scanf("%d\n", &N);

    for(int i = 1; i <= N; ++i) {
        scanf("%d\n", &t);

        for(int j = 1; j <= t; ++j) {
            scanf("%d", &p);

            q.push(-p);
        }
    }

    printf("%d\n", q.size());

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

    return 0;
}