#include<bits/stdc++.h>
using namespace std;
const int N=2e5+5;
int n;
void solve(){
	scanf("%d",&n);
	vector<pair<int, int> > ans;
	for(int i=1;i<=n;++i){
		int x,y;
		scanf("%d",&x);
		while(x--){
			scanf("%d",&y);
			ans.push_back({i,y});
		}
	}
	for(auto [x,y]:ans)
		printf("%d %d\n",x,y);
}
int main(){
	int T;cin>>T;
	while(T--)solve();
}