#include<bits/stdc++.h>
#define fer(i,a,b) for(int i = a ; i <= b ; i ++)
const int N = 2e3 + 10 ;
using namespace std;

int f[N] ;
int a[N][N] ;

int find(int x)
{
    return f[x] == x ? f[x] : f[x] = find(f[x]) ;
}

vector<pair<int,int>> res ;
int id[N] , xia[N][N] ;


void de(vector<int> v)
{
    for(auto i : v)
        cout << i << " " ;
    cout << '\n' ;
}

void merge(int a , int b)
{
    int pa = find(a) , pb = find(b) ;
    if(pa != pb)
    {
        f[pa] = pb ;
        res.push_back({a , b}) ;
    }
}
void solution(){
    int n;
    cin>>n;
    //cout << n << '\n' ;
    res.clear() ;
    fer(i,1,n) f[i] = i , id[i] = 1 ;

    vector<int> v ;
    for(int i = 1 ; i <= n ; i ++)
    {
        fer(j,1,n)
            cin >> a[i][j] ,  xia[i][a[i][j]] = j ;
        if(n >= 2)
            merge(a[i][1] , a[i][2]) ;
        //cout << a[i][n] << '\n' ;
        v.push_back(a[i][n]) ;
    }

    
    for(auto i : v)
    {
        //cout << i << '\n' ;
        for(int j = 1 ; j <= n ; j ++)
        {
            int t = xia[j][i] ;
            if(t + 1 <= n)
            {
                //cout << a[j][1] << " " << a[j][t + 1] << '\n' ;
                merge(a[j][1] , a[j][t + 1]) ;
            }
        }
    }

    for(auto i : res)
        cout << i.first << " " << i.second << '\n' ;

    return ;
}

int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    int T; cin >> T;
    while (T--) solution();
    return 0;
}


/*

1 2 
1 2
3 2
1 2
3 2
4 2
1 2
1 3
2 4
3 5
*/