#include <bits/stdc++.h>
#define Tp template<typename Ty>
#define Ts template<typename Ty,typename... Ar>
#define ll long long
#define CI const int
#define RI int
#define W while
#define gc getchar
#define max(x,y) ((x)>(y)?(x):(y))
#define min(x,y) ((x)<(y)?(x):(y))
#define Mt(a,x) memset((a),(x),sizeof(a))
using namespace std;
namespace SlowIO {
	void Readc (char& c) {W (isspace (c = gc ()));}
	Tp void Read (Ty& x) {char c; int f = 1; x = 0; W (! isdigit (c = gc ())) f = c ^ '-' ? 1 : -1; W (x = (x * 10) + (c ^ 48), isdigit (c = gc ())); x *= f;}
	Ts void Read (Ty& x, Ar&... y) {Read (x); Read (y...);}
} using namespace SlowIO;
CI N = 1e3; int T, n, a[N + 5][N + 5], nxt[N + 5][N + 5], pre[N + 5][N + 5], id[N + 5][N + 5]; bool is[N + 5], vis[N + 5];
void Del (int y) {RI i, j; for (i = 1; i <= n; ++ i) {int now = id[i][y]; nxt[i][pre[i][now]] = nxt[i][now]; pre[i][nxt[i][now]] = pre[i][now];}}
int main () {
	RI i, j; Read (T); W (T --) {
		for (Read (n), i = 1; i <= n; ++ i) for (j = 1; j <= n; ++ j) Read (a[i][j]), id[i][a[i][j]] = j, nxt[i][j] = j + 1, pre[i][j] = j - 1;
		if (n == 2) {printf ("1 2\n"); continue;} Mt (is, 0); Mt (vis, 0); for (i = 1; i <= n; ++ i) nxt[i][0] = 1, pre[i][n + 1] = n; int num = 0; W (num < n - 1) {
			Mt (vis, 0); for (i = 1; i <= n; ++ i) {if (is[i]) continue; vis[a[i][pre[i][n + 1]]] = 1;}
			for (i = 1; i <= n; ++ i) {if (! vis[i]) continue; ++ num; is[i] = 1; printf ("%d %d\n", i, a[i][nxt[i][1]]); Del (i);}
		}
	}
	return 0;
}