#include <bits/stdc++.h>
using namespace std;
/*#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<typename T> using gpp_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename L> using gpp_map = tree<T, L, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T> using gpp_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;*/
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin);i<(end);i++)
#define REP(i, n) FOR(i,0,n)
#define IFOR(i, begin, end) for(int i=(end)-1;i>=(begin);i--)
#define IREP(i, n) IFOR(i,0,n)
#define Sort(v) sort(v.begin(), v.end())
#define Reverse(v) reverse(v.begin(), v.end())
#define all(v) v.begin(),v.end()
#define SZ(v) ((int)v.size())
#define Lower_bound(v, x) distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x) distance(v.begin(), upper_bound(v.begin(), v.end(), x))
#define Max(a, b) a = max(a, b)
#define Min(a, b) a = min(a, b)
#define bit(n) (1LL<<(n))
#define bit_exist(x, n) ((x >> n) & 1)
#define debug(x) cout << #x << "=" << x << endl;
#define vdebug(v) { cout << #v << "=" << endl; REP(i_debug, v.size()){ cout << v[i_debug] << ","; } cout << endl; }
#define mdebug(m) { cout << #m << "=" << endl; REP(i_debug, m.size()){ REP(j_debug, m[i_debug].size()){ cout << m[i_debug][j_debug] << ","; } cout << endl;} }
#define Return(ans) { cout << (ans) << endl; return 0; }
#define pb push_back
#define f first
#define s second
#define int long long
#define INF 1000000000000000000
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for (auto &x : v) is >> x; return is; }
template<typename T> ostream &operator<<(ostream &os, vector<T> &v){ for(int i = 0; i < v.size(); i++) { cout << v[i]; if(i != v.size() - 1) cout << endl; }; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, pair<T1, T2> p){ cout << '(' << p.first << ',' << p.second << ')'; return os; }
template<typename T> void Out(T x) { cout << x << endl; }
template<typename T1, typename T2> void Ans(bool f, T1 y, T2 n) { if(f) Out(y); else Out(n); }

using vec = vector<int>;
using mat = vector<vec>;
using Pii = pair<int, int>;
using PiP = pair<int, Pii>;
using PPi = pair<Pii, int>;
using bools = vector<bool>;
using pairs = vector<Pii>;

//int dx[4] = {1,0,-1,0};
//int dy[4] = {0,1,0,-1};
//char d[4] = {'D','R','U','L'};

const int mod = 1000000007;
//const int mod = 998244353;
//#define Add(x, y) x = (x + (y)) % mod
//#define Mult(x, y) x = (x * (y)) % mod

struct edge { int to, cap, rev, id; };

class Graph
{
public:
    int N;
    vector<vector<edge>> G;
    vector<int> level, iter;

    Graph(int N): N(N){
        G = vector<vector<edge>>(N, vector<edge>(0));
        level = vector<int>(N);
        iter = vector<int>(N);
    }

    //実際の流量を求めたい辺には0以上のidを与える　逆辺のcapを用いる
    void add_Directed_edge(int from, int to, int cap, int id = -1){
        G[from].push_back((edge){to, cap, (int)G[to].size(), -1});
        G[to].push_back((edge){from, 0, (int)G[from].size() - 1, id});
    }

    void bfs(int s){
        memset(&level[0], -1, sizeof(level[0]) * level.size());
        queue<int> que;
        level[s] = 0;
        que.push(s);
        while(!que.empty()){
            int v = que.front(); que.pop();
            REP(i, G[v].size()){
                edge &e = G[v][i];
                if(e.cap > 0 && level[e.to] < 0){
                    level[e.to] = level[v] + 1;
                    que.push(e.to);
                }
            }
        }
    }

    int dfs(int v, int t, int f){
        if(v == t) return f;
        for(int &i = iter[v]; i < G[v].size(); i++){
            edge &e = G[v][i];
            if(e.cap > 0 && level[v] < level[e.to]){
                int d = dfs(e.to, t, min(f, e.cap));
                if(d > 0){
                    e.cap -= d;
                    G[e.to][e.rev].cap += d;
                    return d;
                }
            }
        }
        return 0;
    }

    int max_flow(int s, int t){
        int flow = 0;
        for(;;){
            bfs(s);
            if(level[t] < 0) return flow;
            memset(&iter[0], 0, sizeof(iter[0]) * iter.size());
            int f;
            while((f = dfs(s, t, INF)) > 0) flow += f;
        }
    }

    //実際の流量を求める、max_flow(s, t)を使ってから
    vector<int> calc_flow(int max_id){
        vector<int> flow(max_id + 1, -1);
        REP(v, N) for(auto e: G[v]) if(e.id >= 0) flow[e.id] = e.cap;
        return flow;
    }

};

void dfs(int v, vector<pairs> &es, pairs &ans, bools &used){
    used[v] = true;
    for(Pii q: es[v]) if(!used[q.f]){
        ans[q.s] = Pii(v, q.f);
        dfs(q.f, es, ans, used);
    }
}

signed main(){

    int N; cin >> N;
    vec c(N - 1);
    mat w(N - 1);
    REP(i, N - 1){
        cin >> c[i];
        w[i].resize(c[i]);
        cin >> w[i];
        REP(j, c[i]) w[i][j]--;
    }

    Graph G(2 * N + 2);
    int s = 2 * N, t = s + 1;
    REP(i, N - 1){
        G.add_Directed_edge(s, i, 1);
        G.add_Directed_edge(i + N, t, 1);
    }

    int e = 0;
    pairs info;
    REP(i, N - 1){
        for(int x: w[i]) if(x != N - 1){
            G.add_Directed_edge(i, x + N, 1, e);
            e++;
            info.pb(Pii(i, x + N));
        }
    }
    int f = G.max_flow(s, t);
    vec flow = G.calc_flow(e - 1);

    if(f != N - 1){
        Return(-1);
    }

    vector<pairs> es(N);
    REP(k, e) if(flow[k] == 1){
        int i = info[k].f, x = info[k].s - N;
        for(int y: w[i]){
            es[y].pb(Pii(x, i));
        }
    }
    bools used(N, false);
    pairs ans(N - 1);
    dfs(N - 1, es, ans, used);

    REP(i, N) if(!used[i]){
        Return(-1);
    }
    REP(i, N - 1) cout << ans[i].f + 1 << " " << ans[i].s + 1 << endl;

    return 0;
}


Measured memory_bytes: 71640