//
// Created by yamunaku on 2021/02/19.
//

#include <bits/stdc++.h>
//#include <atcoder/all>

using namespace std;
//using namespace atcoder;

#define rep(i, n) for(int i = 0; i < (n); i++)
#define repl(i, l, r) for(int i = (l); i < (r); i++)
#define per(i, n) for(int i = ((n)-1); i >= 0; i--)
#define perl(i, l, r) for(int i = ((r)-1); i >= (l); i--)
#define all(x) (x).begin(),(x).end()
#define MOD9 998244353
#define MOD1 1000000007
#define IINF 1000000000
#define LINF 1000000000000000000
#define SP <<" "<<
#define CYES cout<<"Yes"<<endl
#define CNO cout<<"No"<<endl
#define CFS cin.tie(0);ios::sync_with_stdio(false)
#define CST(x) cout<<fixed<<setprecision(x)

using ll = long long;
using ld = long double;
using vi = vector<int>;
using mti = vector<vector<int>>;
using vl = vector<ll>;
using mtl = vector<vector<ll>>;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
template<typename T>
using heap = priority_queue<T, vector<T>, function<bool(const T, const T)>>;

int main() {
    //CFS;
    int n;
    cin >> n;
    mti s(n);
    int m = 2000;
    vi use(m);
    mti e(m);
    vi deg(m);
    mti id(m);
    rep(i, n) {
        int k;
        cin >> k;
        s[i] = vi(k);
        rep(j, k) cin >> s[i][j], s[i][j]--;
        use[s[i].back()] = true;
        id[s[i].back()].push_back(i);
    }
    rep(i, n) {
        if (s[i].front() != s[i].back()) {
            if (use[s[i].front()]) {
                e[s[i].front()].push_back(s[i].back());
                deg[s[i].back()]++;
            }
        }
    }
    vi ord;
    queue<int> q;
    rep(i, m) {
        if (deg[i] == 0 && use[i]) q.push(i);
    }
    while (!q.empty()) {
        int now = q.front();
        q.pop();
        ord.push_back(now);
        for (auto &nx : e[now]) {
            deg[nx]--;
            if (deg[nx] == 0) q.push(nx);
        }
    }
    rep(i, m) {
        if (deg[i] > 0) {
            cout << 0 << endl;
            return 0;
        }
    }
    vi ans;
    for (int x : ord) {
        ans.push_back(x);
        for (auto &t : id[x]) {
            int idx = s[t].size() - 1;
            per(i, ans.size()) {
                if (idx >= 0)
                    if (ans[i] == s[t][idx]) {
                        idx--;
                    }
            }
            vi tmp;
            rep(i, idx + 1) {
                tmp.push_back(s[t][i]);
            }
            for (auto &y : ans) tmp.push_back(y);
            ans = tmp;
        }
    }
    cout << ans.size() << endl;
    for (auto &x : ans) cout << x + 1 << " ";
    cout << endl;
    return 0;
}