//Author:xht37
#include <bits/stdc++.h>

#define ui unsigned int
#define ll long long
#define ul unsigned ll
#define ld long double

#define pi pair <int, int>
#define fi first
#define se second
#define mp make_pair

#define ls (p << 1)
#define rs (ls | 1)
#define md ((t[p].l + t[p].r) >> 1)

#define vi vector <int>
#define pb push_back
#define pq priority_queue

#define dbg(x) cerr << #x" = " << x << endl
#define debug(...) fprintf(stderr, __VA_ARGS__)

#define fl(x) freopen(x".in", "r", stdin), freopen(x".out", "w", stdout)

using namespace std;

namespace io {
	const int SI = 1 << 21 | 1;
	char IB[SI], *IS, *IT, OB[SI], *OS = OB, *OT = OS + SI - 1, c, ch[100];
	int f, t;
	#define gc() (IS == IT ? (IT = (IS = IB) + fread(IB, 1, SI, stdin), IS == IT ? EOF : *IS++) : *IS++)
	inline void flush() {
		fwrite(OB, 1, OS - OB, stdout), OS = OB;
	}
	inline void pc(char x) {
		*OS++ = x;
		if (OS == OT) flush();
	}

	template <class I>
	inline void rd(I &x) {
		for (f = 1, c = gc(); c < '0' || c > '9'; c = gc()) if (c == '-') f = -1;
		for (x = 0; c >= '0' && c <= '9'; x = (x << 3) + (x << 1) + (c & 15), c = gc());
		x *= f;
	}
	template <class I>
	inline void rd(I &x, I &y) {
		rd(x), rd(y);
	}
	template <class I>
	inline void rd(I &x, I &y, I &z) {
		rd(x), rd(y), rd(z);
	}
	template <class I>
	inline void rda(I *a, int n) {
		for (int i = 1; i <= n; i++) rd(a[i]);
	}
	inline void rdc(char &c) {
		for (c = gc(); c < 33 || c > 126; c = gc());
	}
	inline void rds(char *s, int &n) {
		for (c = gc(); c < 33 || c > 126; c = gc());
		for (n = 0; c >= 33 && c <= 126; s[++n] = c, c = gc());
		s[n+1] = '\0';
	}
	inline void rds(string &s) {
		for (c = gc(); c < 33 || c > 126; c = gc());
		for (s.clear(); c >= 33 && c <= 126; s.pb(c), c = gc());
	}

	template <class I>
	inline void print(I x, char k = '\n') {
		if (!x) pc('0');
		if (x < 0) pc('-'), x = -x;
		while (x) ch[++t] = x % 10 + '0', x /= 10;
		while (t) pc(ch[t--]);
		pc(k);
	}
	template <class I>
	inline void print(I x, I y) {
		print(x, ' '), print(y);
	}
	template <class I>
	inline void print(I x, I y, I z) {
		print(x, ' '), print(y, ' '), print(z);
	}
	template <class I>
	inline void printa(I *a, int n) {
		for (int i = 1; i <= n; i++) print(a[i], " \n"[i==n]);
	}
	inline void printc(char c) {
		pc(c);
	}
	inline void prints(char *s, int n) {
		for (int i = 1; i <= n; i++) pc(s[i]);
		pc('\n');
	}
	inline void prints(string s) {
		int n = s.length();
		while (t < n) pc(s[t++]);
		pc('\n'), t = 0;
	}
	struct Flush {
		~Flush() {
			flush();
		}
	} flusher;
}
using io::rd;
using io::rda;
using io::rdc;
using io::rds;
using io::print;
using io::printa;
using io::printc;
using io::prints;

namespace Dinic {
	const int N = 2e5 + 7, M = 2e6 + 7;
	const ll inf = 1e18;
	int n, S, T, d[N];
	int h[N], hi[N], e[M], t[M], tot;
	ll f[M], mxf;

	inline void add(int x, int y, ll z, bool o = 1) {
		e[++tot] = y, f[tot] = z, t[tot] = h[x], h[x] = tot;
		if (o) add(y, x, 0, 0);
	}

	inline bool bfs() {
		for (int i = 1; i <= n; i++) d[i] = 0;
		queue<int> q;
		q.push(S), d[S] = 1;
		while (q.size()) {
			int x = q.front();
			q.pop();
			for (int i = h[x]; i; i = t[i]) {
				int y = e[i];
				ll z = f[i];
				if (d[y] || !z) continue;
				q.push(y), d[y] = d[x] + 1;
				if (y == T) return 1;
			}
		}
		return 0;
	}

	ll dfs(int x, ll now = inf) {
		if (x == T) return now;
		ll rst = now;
		for (int &i = hi[x]; i; i = t[i]) {
			int y = e[i];
			ll z = f[i];
			if (d[y] != d[x] + 1 || !z) continue;
			ll k = dfs(y, min(z, rst));
			if (!k) d[y] = 0;
			else f[i] -= k, f[i^1] += k, rst -= k;
			if (!rst) break;
		}
		return now - rst;
	}

	inline void main() {
		while (bfs()) {
			for (int i = 1; i <= n; i++) hi[i] = h[i];
			ll now;
			while ((now = dfs(S))) mxf += now;
		}
	}

	inline void init(int _n, int _S, int _T) {
		n = _n, S = _S, T = _T, tot = 1, mxf = 0;
		for (int i = 1; i <= n; i++) h[i] = 0; 
	}
}
using Dinic::add;

const int N = 1e5 + 7;
int n, f[N], fa[N], id[N];
set<int> e[N], g[N];
bool v[N];
pi ans[N];

int main() {
	rd(n), Dinic::init(2 * n, 1, 2 * n);
	for (int i = 1, c, x; i < n; i++) {
		add(1, i + 1, 1), add(i + n, 2 * n, 1);
		rd(c);
		while (c--) {
			rd(x), e[i].insert(x), g[x].insert(i);
			if (x == 1) continue;
			add(x, i + n, 1);
		}
	}
	Dinic::main();
	if (Dinic::mxf != n - 1) return print(-1), 0;
	for (int x = 1; x < n; x++)
		for (int i = Dinic::h[x+n]; i; i = Dinic::t[i])
			if (Dinic::e[i] <= n && Dinic::f[i]) f[x] = Dinic::e[i];
	queue<int> q;
	q.push(1);
	while (q.size()) {
		int x = q.front();
		q.pop();
		for (int y : g[x])
			if (!v[y]) v[y] = 1, fa[f[y]] = x, id[f[y]] = y, q.push(f[y]);
	}
	for (int i = 1; i < n; i++)
		if (!v[i]) return print(-1), 0;
	for (int i = 2; i <= n; i++) ans[id[i]] = mp(fa[i], i);
	for (int i = 1; i < n; i++) print(ans[i].fi, ans[i].se);
	return 0;
}

Measured memory_bytes: 58876