#include <bits/stdc++.h>
using namespace std;
set <pair<int, int> > mp;
set<pair<int,int> >::iterator it;
bool connect (int x, int y) {
	if (x > y)
		swap(x, y);
	pair<int, int> pii = make_pair(x, y);
	if (mp.count(pii))
		return false;
	mp.insert(pii);
	return true;
}
int tr[1005][1005], vis[1005], h[1005], t[1005], leaf[1005], d[1005], n;
void solve () {
	queue <int> q;
	do {
		if (!q.empty()) {
			int x = q.front();
			q.pop();
			if (t[x] < 1 || vis[x])
				continue;
			while (vis[tr[x][t[x]]] && t[x] > 1) {
				t[x]--;
			}
			if (t[x] >= 1) {
				vis[tr[x][t[x]]] = 1;
			}
		}
		for (int i = 1; i <= n; i++) {
			if (h[i] > n || vis[i])
				continue;
			while (vis[tr[i][h[i]]] && h[i] <= n) {
				h[i]++;
			}
			if (h[i] <= n) {
				connect(i, tr[i][h[i]]);
			}
		}
		for (int i = 1; i <= n; i++) {
			while (vis[t[i]])
				t[i]--;
			if (t[i] >= 1)
				q.push(i);
		}
	}while (!q.empty());
	return;
}
void print () {
	for (it = mp.begin(); it != mp.end(); it++) {
		printf("%d %d\n", it->first, it->second);
	}
	mp.clear();
	return;
}
int main () {
	int T;
	scanf("%d", &T);
	while (T--) {
		scanf("%d", &n);
		for (int i = 1; i <= n; i++) {
			vis[i] = 0;
			h[i] = 2;
			t[i] = n;
		}
		for (int i = 1; i <= n; i++) {
			for (int j = 1; j <= n; j++) {
				scanf("%d", &tr[i][j]);
			}
		}
		solve();
		print();
	}
	return 0;
}