#include<iostream>
#include<algorithm>
#include<string.h>
#include<vector>
using namespace std;
// #define debug(x) cout<<"[debug]"#x<<"="<<x<<endl
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
const ld eps=1e-8;
const int INF=0x3f3f3f3f,mod=998244353;

#define ONLINE_JUDGE
#ifndef ONLINE_JUDGE
#define debug(...)
#include<debug>
#else
#define debug(...)
#endif

const int N=1003;
int a[N][N];
int id[N];
bool vis[N];
vector<pii> path;
void solve()
{
    path.clear();
    int n;
    scanf("%d",&n);
    for(int i=1;i<=n;i++) vis[i]=false;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n;j++) scanf("%d",&a[i][j]);
        id[a[i][1]]=i;
    }
    for(int i=n;i>=1;i--)
    {
        int j=id[a[1][i]];
        vis[a[j][1]]=true;
        if(n>=2&&!vis[a[j][2]]) path.push_back({a[j][1],a[j][2]});
    }

    for(auto [x,y]:path) printf("%d %d\n",x,y);
    puts("");
}
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        solve();
    }
}