#include <iostream>
#include <algorithm>
#include <cstring>
#include <vector>
#include <array>
#include <queue>
#include <cmath>
using namespace std;
#define int long long
#define endl '\n'
typedef pair<int,int> PII;
const int N = 1e3 + 10,mod = 998244353,INF = 1e18;
int g[N][N],n,T;
bool leaf[N],has[N][N];
int p[N];
vector<int> e[N];

int find(int x)
{
	if(p[x] != x) p[x] = find(p[x]);
	return p[x];
}

void solve()
{
    cin >> n;
    for(int i = 1;i <= n;i++) leaf[i] = false,p[i] = i,e[i].clear();
    for(int i = 1;i <= n;i++)
    	for(int j = 1;j <= n;j++)
    		has[i][j] = false;
    for(int i = 1;i <= n;i++)
    {
        for(int j = 1;j <= n;j++)
        {
        	cin >> g[i][j];
        	if(j == n) leaf[g[i][j]] = true;
		}
    }
    if(n == 1)
    {
    	return ;
	}
	for(int i = 1;i <= n;i++)
	{
		int x = g[i][1],y = g[i][2];
		if(x > y) swap(x,y);
		if(!has[x][y])
		{
			e[x].push_back(y);
			has[x][y] = true;
		}
		if(p[find(x)] != p[find(y)])
		{
			if(!leaf[find(y)]) p[find(x)] = find(y);
			else p[find(y)] = find(x);
		}
	}
	int cur = p[find(1)];
	for(int i = 1;i <= n;i++)
	{
		if(p[find(i)] != cur)
		{
			e[cur].push_back(p[find(i)]);
			p[find(i)] = cur;
		}
	}
	for(int i = 1;i <= n;i++)
	{
		for(auto item : e[i])
		{
			cout << i << ' ' << item << endl;
		}
	}
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> T;
    while(T--)
    {
        solve();
    }
}