#include "Memory2_lib.h"
#include<bits/stdc++.h>

#define pii pair<int, int>
#define mkp make_pair
#define rep(i, a, b) for(int i = (a); i <= (b); ++i)

using namespace std;

const int N = 55;

int n;
set <pii> S[N];

inline void add (int x, int y) { S[Flip (x, y)].insert (mkp (x, y)); }

inline int getnxt () {
	rep (i, 0, n - 1) if (S[i].size () > 1) return i;
	return - 1;
}

void Solve(int sid, int nn){
	n = nn;
	for (int i = 0; i < 2 * n; i += 2) add (i, i + 1);
	
	int w;
	while ((w = getnxt ()) != - 1) {
		auto [u, v] = *S[w].begin ();
		auto [x, y] = *S[w].rbegin ();
		S[w].clear ();
		if (Flip (u, x) != w)      Answer (v, y, w), add (u, x);
		else if (Flip (u, y) != w) Answer (v, x, w), add (u, y);
		else if (Flip (v, x) != w) Answer (u, y, w), add (v, x);
		else 			   Answer (u, x, w), add (v, y);
	}
	
	rep (i, 0, n - 1) if (!S[i].empty ()) {
		auto [u, v] = *S[i].begin ();
		Answer (u, v, i);
	}
	
	
	return;
}