#include<bits/stdc++.h>
#define to edge[i].v
#define mp make_pair
#define rint register int
#define debug(x) cerr<<#x<<"="<<x<<endl
#define fgx cerr<<"-------------"<<endl
#define N 200010
#define T n+n+1
#define add(x,y,z) addedge(x,y,z),addedge(y,x,0)
using namespace std;
typedef long long ll;
typedef long double db;
typedef pair<int,int> pii;
int head[N],tot=1,cur[N],vis[N],dis[N],n,p[N],fa[N],s; vector<int> v[N];
struct Edge{int v,next,f,w;}edge[N*10]; queue<int> q;
inline void addedge(int x,int y,int z){edge[++tot]=Edge{y,head[x],0,z};head[x]=tot;}
inline int bfs()
{	memset(vis,0,sizeof(vis)); memcpy(cur,head,sizeof(cur)); q.push(0); vis[0]=1;
	while(!q.empty())
	{	int x=q.front(); q.pop();
		for(rint i=head[x];i;i=edge[i].next)
		if(!vis[to]&&edge[i].f<edge[i].w) dis[to]=dis[x]+1,vis[to]=1,q.push(to);
	}
	return vis[T];
}
int dfs(int x,int res)
{	if(x==T||!res) return res; int flow=0,f;
	for(rint &i=cur[x];i;i=edge[i].next)
	if(dis[to]==dis[x]+1&&(f=dfs(to,min(res,edge[i].w-edge[i].f))))
	{edge[i].f+=f;edge[i^1].f-=f;res-=f;flow+=f;if(!res)break;}
	return flow;
}
inline int dinic(){int A=0;while(bfs())A+=dfs(0,INT_MAX);return A;}
void dfs(int x){vis[x]=1;s++;for(auto y:v[x])if(!vis[p[y]])fa[y]=x,dfs(p[y]);}
int main()
{	int m,x; cin>>n; for(rint i=1;i<=n;i++) add(n+i,T,1);
	for(rint i=1;i<n;add(0,i,1),i++)
	for(scanf("%d",&m);m--;){scanf("%d",&x),v[x].push_back(i);if(x!=1)add(i,n+x,1);}
	if(dinic()!=n-1) return !printf("-1");
	for(rint j=1;j<n;j++)
	for(rint i=head[j];i;i=edge[i].next) if(n<to&&to<=n+n&&edge[i].f) p[j]=to-n;
	dfs(1); if(s!=n) return !printf("-1");
	for(rint i=1;i<n;i++) printf("%d %d\n",fa[i],p[i]);
	return 0;
}
