#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using i128 = __int128;
const ll base = 37;
const ll mod = 998244353;
const int inf = 1e9+5;
const int maxn = 1e5+5;
const ll linf = 1e18+5ll;
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t;
    cin>>t;
    while(t--) {
        int n;
        cin>>n;
        vector<int>g[n+1];
        vector<int>vis(n+1);
        for(int i = 1;i<=n;i++) {
            g[i].resize(n+1);
            for(int j = 1;j<=n;j++) {
                cin>>g[i][j];
            }
        }
        vector<array<int,2>>ans;
        for(int i = 1;i<=n;i++) {
            while(vis[g[i].back()]) {
                g[i].pop_back();
            }
            int u = g[i].back();
            int v = -1;
            for(int j = 1;j<=n;j++) {
                if(vis[g[u][j]] == 0 && u != g[u][j]) {
                    v = g[u][j];
                    break;
                }
            }
            vis[u] = 1;
            if(v != -1)
                ans.push_back({u,v});
        }
        assert((int)ans.size() == n-1);
        for(auto [u,v] : ans) {
            cout<<u<<" "<<v<<endl;
        }
    }
    return 0;
}