#include <bits/stdc++.h>

using i64 = int64_t;

namespace stdr = std::ranges;
namespace stdv = std::views;

struct DSU {
    std::vector<int> f, siz;

    DSU() {}
    DSU(int n) {
        init(n);
    }

    void init(int n) {
        f.resize(n);
        std::iota(f.begin(), f.end(), 0);
        siz.assign(n, 1);
    }

    constexpr int find(int x) {
        while (x != f[x]) {
            x = f[x] = f[f[x]];
        }
        return x;
    }
    constexpr int operator[](int i) {
        return find(i);
    }

    bool same(int x, int y) {
        return find(x) == find(y);
    }

    bool merge(int x, int y, bool t = true) {
        x = find(x);
        y = find(y);
        if (x == y) {
            return false;
        }
        if (t && siz[x] < siz[y]) {
            std::swap(x, y);
        }
        siz[x] += siz[y];
        f[y] = x;
        return true;
    }

    int size(int x) {
        return siz[find(x)];
    }
};

void solve() {
    int n;
    std::cin >> n;

    std::vector a(n, std::vector<int>(n));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            std::cin >> a[i][j];
            a[i][j]--;
        }
    }

    std::set<std::pair<int, int>> ans;
    DSU dsu(n);
    for (int j = 0; j < n && ans.size() < n - 1; j++) {
        for (int i = 0; i < n && ans.size() < n - 1; i++) {
            if (dsu.merge(a[i][0], a[i][j])) {
                ans.emplace(a[i][0], a[i][j]);
            }
        }
    }

    for (auto [x, y] : ans) {
        std::cout << x + 1 << " " << y + 1 << "\n";
    }
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    int t;
    std::cin >> t;

    while (t--) {
        solve();
    }

    return 0;
}