#include <iostream>
#include <vector>

using namespace std;

long long n, s, t = 1, a, b, sum = 0;
vector<long long> G;
vector<int> v;

void Eulerian(int q){
    for(int k = 1; k <= n; k++){
        if (G[q][k] > 0){
            G[q][k]--;
            G[k][q]--;
            Eulerian(k);
        }
    }
    v.push_back(q);
}

int main() {
    cin >> n;
    G.assign(n + 1, vector<int>(n + 1, 0));
    for(int i = 1; i <= n; i++){
        cin >> s;
        sum += s;
        if (s % 2 != 0)
            t = i;
        for (int j = 1; j <= s; j++){
            cin >> a >> b;
            G[i][a]++;
        }
    }
    Eulerian(t);
    cout << sum / 2 << "\n";
    for(int k = v.size() - 1; k >= 0; k--){
        cout << v[k] << " ";
    }
    return 0;
}