#include <fstream> 
#include <vector>
#include <chrono>
#include <queue>
using namespace std;
ifstream cin("interclasari.in");
ofstream cout("interclasari.out");
struct pqueue {
	int val;
	bool operator <(const pqueue a) const {
		return val > a.val;
	}
};
int main() {
	priority_queue<pqueue> q;
	int k;
	cin >> k;
	while (k--) {
		int n,x;
		cin >> n;
		while (n--) {
			cin >> x;
			q.push({ x });
		}
	}
	cout << q.size() << '\n';
	while (!q.empty()) {
		cout << q.top().val << ' ';
		q.pop();
	}
}